Method and apparatus for performing frequency measurement and setting frequency measurement for non-connection mode terminal

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 16/983,544,filed Aug. 3, 2020, now U.S. Pat. No. 11,343,690, which is based on andclaims priority under 35 U.S.C. 119 to Korean Patent Application No.10-2019-0094585, filed on Aug. 2, 2019 and Korean Patent Application No.10-2019-0107685 filed on Aug. 30, 2019, in the Korean IntellectualProperty Office, the disclosures of which are herein incorporated byreference in their entireties.

BACKGROUND 1. Field

The disclosure relates to a method and apparatus for performing afrequency measurement and setting the frequency measurement for anon-connection mode terminal in a next generation mobile communicationsystem.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud radio access networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,coordinated multi-points (CoMP), reception-end interference cancellationand the like. In the 5G system, hybrid FSK and QAM modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, machine type communication (MTC), andmachine-to-machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud radioaccess network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

In order to support a service having a high data rate and a lowtransmission delay in a next generation mobile communication system, abase station needs to quickly configure a carrier aggregation (CA)technology or a dual connectivity (DC) technology to a terminal.However, configuring the above technologies to the terminal requires afrequency measurement result of the terminal. Therefore, there is a needfor a method to quickly receive a report of the frequency measurementresult from the terminal.

SUMMARY

According to various embodiments of the disclosure,

The disclosure proposes a method for a terminal of an RRC idle mode oran RRC inactive mode to quickly report a result of measuring ambientfrequencies to a base station in a next generation mobile communicationsystem, thereby allowing the base station to quickly configure the CAtechnology or DC technology to the terminal. Specifically, the basestation may set configuration information for the frequency measurementin an RRC message to the terminal that has capability of performing thefrequency measurement in the RRC idle mode or the RRC inactive mode whenthe terminal releases a connection with a network. While moving in theRRC idle mode or the RRC inactive mode and performing a cell selectionor reselection procedure, the terminal may perform the frequencymeasurement based on frequency measurement configuration information setin the RRC message or system information of a serving cell on which theterminal camps through the cell reselection procedure. In addition, thebase station may quickly configure the CA technology or the DCtechnology to the terminal by allowing the terminal to report thefrequency measurement result immediately upon establishing theconnection with the network.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certainembodiments of the disclosure will be more apparent from the followingdetailed description, taken in conjunction with the accompanyingdrawings.

FIG. 1 is a diagram illustrating a structure of a long term evolution(LTE) system according to an embodiment of the disclosure.

FIG. 2 is a diagram illustrating a structure of a radio protocol in anLTE system according to an embodiment of the disclosure.

FIG. 3 is a diagram illustrating a structure of a next generation mobilecommunication system according to an embodiment of the disclosure.

FIG. 4 is a diagram illustrating a structure of a radio protocol in anext generation mobile communication system according to an embodimentof the disclosure.

FIG. 5 is a diagram illustrating a procedure of a terminal to transitionfrom an RRC idle mode or an RRC inactive mode to an RRC connected modeand configure a carrier aggregation technology in a next generationmobile communication system according to an embodiment of thedisclosure.

FIG. 6 is a diagram illustrating a first embodiment enabling a terminalto perform an early measurement in an RRC idle mode or an RRC inactivemode and make an early measurement report in a next generation mobilecommunication system according to an embodiment of the disclosure.

FIG. 7 is a diagram illustrating a second embodiment enabling a terminalto perform an early measurement in an RRC idle mode or an RRC inactivemode and make an early measurement report in a next generation mobilecommunication system according to an embodiment of the disclosure.

FIG. 8 is a diagram illustrating a signal structure when a terminalperforms a frequency measurement for an LTE frequency in an RRC idlemode or an RRC inactive mode according to an embodiment of thedisclosure.

FIGS. 9 and 10 are diagrams each illustrating a signal structure when aterminal performs a frequency measurement for an NR frequency in an RRCidle mode or an RRC inactive mode according to an embodiment of thedisclosure.

FIG. 11 is a diagram illustrating a method for a terminal to perform afrequency measurement in an RRC idle mode or an RRC inactive mode in anetwork that is synchronized between different frequencies or cellsaccording to an embodiment of the disclosure.

FIG. 12 is a diagram illustrating a problem that occurs when a terminalperforms a frequency measurement in an RRC idle mode or an RRC inactivemode in a network that is not synchronized between different frequenciesor cells according to an embodiment of the disclosure.

FIG. 13 is a diagram illustrating a first embodiment of an efficientfrequency measurement method in an RRC idle mode or an RRC inactive modeaccording to an embodiment of the disclosure.

FIG. 14 is a diagram illustrating a second embodiment of an efficientfrequency measurement method in an RRC idle mode or an RRC inactive modeaccording to an embodiment of the disclosure.

FIG. 15 is a diagram illustrating a third embodiment of an efficientfrequency measurement method in an RRC idle mode or an RRC inactive modeaccording to an embodiment of the disclosure.

FIG. 16 is a diagram illustrating a fourth embodiment of an efficientfrequency measurement method in an RRC idle mode or an RRC inactive modeaccording to an embodiment of the disclosure.

FIG. 17 is a diagram illustrating a method for a terminal to perform afrequency measurement in an RRC idle mode or an RRC inactive mode in anetwork that is not synchronized between different frequencies or cellsaccording to an embodiment of the disclosure.

FIG. 18 is a diagram illustrating operations of a terminal to perform afrequency measurement in an RRC idle mode or an RRC inactive mode andreport a measurement result according to an embodiment of thedisclosure.

FIG. 19 is a block diagram illustrating a structure of a terminalaccording to an embodiment of the disclosure.

FIG. 20 is a block diagram illustrating a structure of a base station ina wireless communication system according to an embodiment of thedisclosure.

DETAILED DESCRIPTION

FIGS. 1 through 20, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

In describing the disclosure below, a detailed description of relatedknown configurations or functions incorporated herein will be omittedwhen it is determined that the detailed description thereof mayunnecessarily obscure the subject matter of the disclosure. Hereinafter,embodiments of the disclosure will be described with reference to theaccompanying drawings.

In the descriptions below, a term used for identifying an access node,terms indicating network entities, terms indicating messages, a termindicating an interface between network entities, terms indicatingvarious pieces of identification information, and the like are used forease of description. Therefore, the disclosure may not be limited by theterminologies provided below, and other terms that indicate subjectshaving equivalent technical meanings may be used.

For ease of description, the disclosure uses terms and names defined inthe 3rd generation partnership project long term evolution (3GPP LTE).However, the disclosure is not limited to the terms and the names, andmay be equally applied to systems that comply with other standards. Forease of description, an evolved nodeB (eNB) and a “gNB” may beinterchangeably used in the disclosure. That is, a base station that isdescribed as eNB may indicate gNB.

The disclosure proposes a method for a terminal of an RRC idle mode oran RRC inactive mode to quickly report a result of measuring ambientfrequencies to a base station in a next generation mobile communicationsystem, thereby allowing the base station to quickly configure a carrieraggregation (CA) technology or a dual connectivity (DC) technology tothe terminal. Specifically, the base station may set configurationinformation for the frequency measurement in an RRC message to theterminal that has capability of performing the frequency measurement inthe RRC idle mode or the RRC inactive mode when the terminal releases aconnection with a network. While moving in the RRC idle mode or the RRCinactive mode and performing a cell selection or reselection procedure,the terminal may perform the frequency measurement based on frequencymeasurement configuration information set in the RRC message or systeminformation of a serving cell on which the terminal camps through thecell reselection procedure. In addition, the base station may quicklyconfigure the CA technology or the DC technology to the terminal byallowing the terminal to report the frequency measurement resultimmediately upon establishing the connection with the network.

In the disclosure, an RRC connected mode terminal may receive an RRCmessage (e.g., an RRCRelease message) from a base station and release anRRC connection. If the RRC message contains frequency measurementconfiguration information together with instructions to transition to anRRC idle mode or an RRC inactive mode, the terminal may perform afrequency measurement in the RRC idle mode or the RRC inactive modeduring a given duration or time. However, if there is no informationabout a list of frequencies to be measured in the frequency measurementconfiguration information set through the RRC message, and if a servingcell on which the terminal camps through a cell selection or reselectionprocedure broadcasts the frequency measurement configuration informationfor the frequency measurement of an RRC idle mode or RRC inactive modeterminal, the terminal may perform the frequency measurement by storingor considering a frequency measurement list based on the information.

As described above, the terminal may perform the frequency measurementin the RRC idle mode or the RRC inactive mode. If there is a need toestablish an RRC connection with a network, and if there is an indicatorindicating a support of the RRC idle mode or RRC inactive mode frequencymeasurement (Early measurement) in the system information of the servingcell, or there is in the terminal a valid measurement result thatsatisfies a measurement result report condition set in the frequencymeasurement configuration information, the RRC idle mode or RRC inactivemode terminal may transmit, to the base station through an RRC message(e.g., an RRCSetupComplete message or an RRCResumeComplete message), anindicator indicating that there is a result of performing the frequencymeasurement in the RRC idle mode or the RRC inactive mode. Uponreceiving the indicator, the base station may transmit a request message(e.g., a new RRC message or a UElnformationRequest message) requestingthe frequency measurement result to the terminal. Upon receiving therequest message, the terminal may report the frequency measurementresult as a response message (e.g., a new RRC message or aUElnformationResponse message) to the base station. Thus, based on themeasurement result, the base station may quickly configure the CAtechnology or the DC technology to the terminal.

In another method, if the terminal performs the frequency measurement inthe RRC inactive mode and has a need to establish an RRC connection witha network, and if there is an indicator indicating a support of the RRCidle mode or RRC inactive mode frequency measurement (Early measurement)in the system information of the serving cell, or there is in theterminal a valid measurement result that satisfies a measurement resultreport condition set in the frequency measurement configurationinformation, the RRC inactive mode terminal may report, upon receivingfrom the base station an RRC message (e.g., an RRCResume message)containing an indicator requesting the frequency measurement result, avalid frequency measurement result as an RRC message to the basestation. Thus, based on the measurement result, the base station mayquickly configure the CA technology or the DC technology to theterminal.

The disclosure proposes which configuration information the base stationshould transmit to the terminal for battery saving and efficientsignaling of the terminal when setting the RRC idle mode or RRC inactivemode frequency measurement configuration information to the terminal,and which configuration information the base station should transmit inthe RRC message (e.g., the RRCRelease message) or system information.

In addition, the disclosure proposes how the terminal will perform thefrequency measurement for each frequency or cell in order to save thebattery of the terminal when receiving the RRC idle mode or RRC inactivemode frequency measurement configuration information through the RRCmessage or system information, and how the terminal will apply thefrequency measurement configuration information received through the RRCmessage or system information when performing the frequency measurement.

FIG. 1 is a diagram illustrating a structure of a long term evolution(LTE) system to according to an embodiment of the disclosure.

Referring to FIG. 1, as illustrated, a radio access network of an LTEsystem is configured with next generation base stations (an evolved nodeB (ENB), a Node B, or a base station) 1-05, 1-10, 1-15, and 1-20, amobility management entity (MME) 1-25, and a serving-gateway (S-GW)1-30. A user equipment (UE) (or a terminal) 1-35 may access an externalnetwork via the ENB 1-05 to 1-20 and the S-GW 1-30.

In FIG. 1, the ENB 1-05 to 1-20 may correspond to a legacy node B in auniversal mobile telecommunications system (UMTS). The ENB is connectedto the UE 1-35 via a wireless channel, and performs a more complicatedrole than the legacy node B. In the LTE system, real-time services, suchas a voice over IP (VoIP) via an Internet protocol, and all user trafficmay be provided via a shared channel. Accordingly, there is a desire fora device that performs scheduling by collecting state information ofUEs, such as a buffer state, an available transmission power state, achannel state, and the like, and the ENB 1-05 to 1-20 may be in chargeof scheduling. One ENB generally controls a plurality of cells. In orderto implement a transmission rate of 100 Mbps, the LTE system uses anorthogonal frequency division multiplexing (OFDM) as a wireless accesstechnology in a bandwidth of 20 mega-Hertz (MHz). In addition, anadaptive modulation & coding (AMC) scheme that determines a modulationscheme and a channel coding rate may be applied based on the channelstate of the UE. The S-GW 1-30 is a device for providing a data bearer,and generates or removes a data bearer under the control of the MME1-25. The MME is a device that is in charge of various control functionsin addition to a mobility management function associated with the UE,and may be connected to a plurality of base stations.

FIG. 2 is a diagram illustrating a structure of a radio protocol in anLTE system according to an embodiment of the disclosure.

Referring to FIG. 2, the radio protocol of the LTE system includes, foreach of a UE and an ENB, a packet data convergence protocol (PDCP) 2-05and 2-40, a radio link control (RLC) 2-10 and 2-35, a medium accesscontrol (MAC) 2-15 and 2-30, and a physical layer (PHY) 2-20 and 2-25.The PDCP 2-05 and 2-40 may take charge of IP headercompression/decompression, or the like. The main functions of the PDCPmay be summarized as follows:

-   -   Header compression and decompression: robust header compression        (ROHC) only    -   Transfer of user data    -   In-sequence delivery (In-sequence delivery of upper layer packet        data units (PDUs) at PDCP re-establishment procedure for radio        link control acknowledged mode (RLC AM))    -   Reordering (For split bearers in DC (only support for RLC AM):        PDCP PDU routing for transmission and PDCP PDU reordering for        reception)    -   Duplicate detection (Duplicate detection of lower layer service        data units (SDUs) at PDCP re-establishment procedure for RLC AM)    -   Retransmission (Retransmission of PDCP SDUs at handover and, for        split bearers in DC, of PDCP PDUs at PDCP data-recovery        procedure, for RLC AM)    -   Ciphering and deciphering    -   Timer-based SDU discard (Timer-based SDU discard in uplink)

The RLC 2-10 and 2-35 may reconfigure a PDCP PDU into an appropriatesize, and perform ARQ or the like. The main functions of an RLC may besummarized as follows:

-   -   Transfer of data (Transfer of upper layer PDUs)    -   Automatic repeat query (ARQ) (Error correction through ARQ (only        for AM data transfer))    -   Concatenation, segmentation, and reassembly (Concatenation,        segmentation and reassembly of RLC SDUs (only for un-acknowledge        mode (UM) and AM data transfer))    -   Re-segmentation (Re-segmentation of RLC data PDUs (only for AM        data transfer))    -   Reordering (Reordering of RLC data PDUs (only for UM and AM data        transfer)    -   Duplicate detection (Duplicate detection (only for UM and AM        data transfer))    -   Error detection (Protocol error detection (only for AM data        transfer))    -   RLC SDU discard (RLC SDU discard (only for UM and AM data        transfer))    -   RLC re-establishment

The MAC 2-15 and 2-30 may be connected to various RLC layer devicesconfigured for one UE, and may perform multiplexing of RLC PDUs to a MACPDU and demultiplexing of RLC PDUs from a MAC PDU. The main functions ofthe MAC may be summarized as follows:

-   -   Mapping (Mapping between logical channels and transport        channels)    -   Multiplexing and demultiplexing (Multiplexing/demultiplexing of        MAC SDUs belonging to one or different logical channels        into/from transport blocks (TB) delivered to/from the physical        layer on transport channels)    -   Scheduling information reporting    -   Hybrid automatic repeat request (HARQ) (error correction through        HARQ)    -   Priority handling between logical channels (Priority handling        between logical channels of one UE)    -   Priority handling between UEs (Priority handling between UEs by        means of dynamic scheduling)    -   Multimedia broadcast/multicast service (MBMS) service        identification    -   Transport format selection    -   Padding

The physical (PHY) layer 2-20 and 2-25 may perform an operation ofchannel-coding and modulating higher layer data to produce an OFDMsymbol and transmitting the OFDM symbol to a wireless channel, ordemodulating and channel-decoding an OFDM symbol received via a wirelesschannel and transmitting the demodulated and channel-decoded OFDM symbolto a higher layer.

FIG. 3 is a diagram illustrating a structure of a next generation mobilecommunication system according to an embodiment of the disclosure.

Referring to FIG. 3, as illustrated, a radio access network of the nextgeneration mobile communication system (hereinafter NR or 5G) may beconfigured with a next generation base station (new radio node B (NR gNBor NR base station) 3-10 and a new radio core network (NR CN) 3-05. Auser equipment (new radio user equipment (NR UE) or terminal) 3-15 mayaccess an external network 3-35 via the NR gNB 3-10 and the NR CN 3-05.

In FIG. 3, the NR gNB 3-10 may correspond to an evolved Node B (eNB) inthe legacy LTE system. The NR gNB is connected to the NR UE 3-15 via awireless channel, and may provide a better service compared to thelegacy nodeB. In the next generation mobile communication system, alluser traffics are serviced via a shared channel and thus, a device thatcollects state information of UEs, such as a buffer status, an availabletransmission power status, a channel status or the like, and performsscheduling is needed, and the NR NB 3-10 takes charge of the same. OneNR gNB generally controls a plurality of cells. In order to implementhigh-speed data transmission when compared to the currently used LTE, abandwidth greater than or equal to the legacy maximum bandwidth may beneeded, and an orthogonal frequency division multiplexing (OFDM) is usedas a radio access technology, and beamforming technology is additionallyused. Also, an adaptive modulation & coding (AMC) scheme that determinesa modulation scheme and a channel coding rate may be applied based onthe channel state of a UE. The NR CN 3-05 may support mobility,configures a bearer, or configures quality of service (QoS). The NR CN3-05 is a device that is in charge of various control functions inaddition to a mobility management function associated with the UE 3-15,and may be connected to a plurality of base stations. Also, the nextgeneration mobile communication system may interoperate with the legacyLTE system, and the NR CN 3-05 may be connected to the MME 3-25 via anetwork interface. The MME 3-25 may be connected to the eNB 3-30 whichis a legacy base station.

FIG. 4 is a diagram illustrating a structure of a radio protocol in anext generation mobile communication system according to an embodimentof the disclosure.

Referring to FIG. 4, a radio protocol of a next generation mobilecommunication system is configured with an NR service data adaptationprotocol (SDAP) 4-01 and 4-45, an NR PDCP 4-05 and 4-40, an NR RLC 4-10and 4-35, and an NR MAC 4-15 and 4-30 for each of a UE and an NR basestation.

The main functions of the NR SDAP 4-01 and 4-45 may include a part ofthe functions as follows:

-   -   Transfer of user data (Transfer of user plane data)    -   Mapping between a QoS flow and a data radio bearer (DRB) for        both downlink (DL) and uplink (UL)    -   Marking QoS flow identify (ID) for both DL and UL (Marking QoS        flow ID in both DL and UL packets)    -   Mapping reflective QoS flow to DRB for the UL SDAP PDUs        (Reflective QoS flow to DRB mapping for the UL SDAP PDUs)

A UE may receive, via an radio resource control (RRC) message, aconfiguration associated with whether to use a header of the SDAP layerdevice or whether to use a function of the SDAP layer device, for eachPDCP layer device, or for each bearer, or for each logical channel Whena SDAP header is configured, the UE is directed, by a one-bit non-accessstratum (NAS) reflective QoS indicator (NAS reflective QoS) and aone-bit AS reflective QoS indicator (AS reflective QoS) of the SDAPheader, to update or reconfigure mapping information between a databearer and a QoS flow of an uplink and a downlink. The SDAP header mayinclude QoS flow ID information indicating QoS. The QoS information maybe used as data processing priority for supporting smooth services,scheduling information or the like.

The main functions of the NR PDCP 4-05 and 4-40 may include a part ofthe functions as follows:

-   -   Header compression and decompression: ROHC only    -   Transfer of user data    -   In-sequence delivery (In-sequence delivery of upper layer PDUs)    -   Out-of-sequence delivery (Out-of-sequence delivery of upper        layer PDUs)    -   Reordering (PDCP PDU reordering for reception)    -   Duplicate detection (Duplicate detection of lower layer SDUs)    -   Retransmission (Retransmission of PDCP SDUs)    -   Ciphering and deciphering    -   Timer-based SDU discard (Timer-based SDU discard in uplink)

The reordering function of the NR PDCP 4-05 and 4-40 may indicate afunction of reordering PDCP PDUs received from a lower layersequentially according to a PDCP sequence number (SN). The reorderingfunction may include a function of sequentially transferring reordereddata to a higher layer, may include a function of immediatelytransferring data without considering order, may include a function ofperforming reordering and recording lost PDCP PDUs, may include afunction of reporting the states of lost PDCP PDUs to a transmissionside, and may include a function of requesting retransmission of lostPDCP PDUs.

The main functions of the NR RLC 4-10 and 4-35 may include a part of thefunctions as follows:

-   -   Transfer of data (Transfer of upper layer PDUs)    -   In-sequence delivery (In-sequence delivery of upper layer PDUs)    -   Out-of-sequence delivery (Out-of-sequence delivery of upper        layer PDUs)    -   ARQ (Error correction through ARQ)    -   Concatenation, segmentation, and reassembly (Concatenation,        segmentation and reassembly of RLC SDUs)    -   Re-segmentation (Re-segmentation of RLC data PDUs)    -   Reordering (Reordering of RLC data PDUs)    -   Duplicate detection    -   Error detection (Protocol error detection)    -   RLC SDU discard    -   RLC re-establishment

The in-sequence delivery function of the NR RLC device may indicate afunction of sequentially transferring RLC SDUs, received from a lowerlayer, to a higher layer. The in-sequence delivery function may includea function of reassembling RLC SDUs, which are segmented from anoriginally single RLC SDU, and transferring an RLC SDU, may include afunction of reordering received RLC PDUs based on an RLC sequence number(SN) or PDCP sequence number (SN), may include a function of performingreordering and recording lost RLC PDUs, may include a function ofreporting the states of lost RLC PDUs to a transmission side, mayinclude a function of requesting retransmission of lost RLC PDUs, mayinclude a function of sequentially transferring, to a higher layer, onlyRLC SDUs before a lost RLC SDU if a lost RLC SDU exists, may include afunction of sequentially transferring, to a higher layer, all RLC SDUreceived before a timer starts if the timer expires although a lost RLCSDU exists, or may include a function of sequentially transferring, to ahigher layer, all RLC SDUs received up to date, if a predetermined timerexpires, although a lost RLC SDU exists. The RLC PDUs may be processedin order of arrival (irrespective of a sequence number) and may betransferred to a PDCP device randomly (out-of sequence delivery). In thecase of segments, a single RLC PDU is reconfigured by receiving segmentswhich are stored in a buffer or are to be received in the future, andthe RLC PDU may be transferred to the PDCP device. The NR RLC layer 4-10and 4-35 may not include a concatenation function, and the function maybe performed by the NR MAC layer 4-15 and 4-30 or may be replaced withthe multiplexing function of the NR MAC layer 4-10 and 4-35.

The out-of-sequence deliver function of the NR RLC device may indicate afunction of immediately transferring RLC SDUs, received from a lowerlayer, to a higher layer in any order. The out-of sequence deliveryfunction may include a function of reassembling RLC SDUs which aresegmented from an originally single RLC SDU, and transferring an RLCSDU, and may include a function of storing an RLC SN or PDCP SN ofreceived RLC PDUs, performing reordering, and recording lost RLC PDUs.

The NR MAC layer 4-15 and 4-30 may be connected to a plurality of NR RLClayer devices configured for a single UE, and the main functions of theNR MAC 4-15 and 4-30 may include a part of the functions as follows:

-   -   Mapping (Mapping between logical channels and transport        channels)    -   Multiplexing/demultiplexing (Multiplexing/demultiplexing of MAC        SDUs)    -   Scheduling information reporting    -   HARQ (Error correction through HARQ)    -   Priority handling between logical channels (Priority handling        between logical channels of one UE)    -   Priority handling between UEs (Priority handling between UEs by        means of dynamic scheduling)    -   MBMS service identification    -   Transport format selection    -   Padding

The NR PHY layer 4-20 and 4-25 may perform an operation ofchannel-coding and modulating higher layer data to produce an OFDMsymbol and transmitting the OFDM symbol to a wireless channel, ordemodulating and channel-decoding an OFDM symbol received via a wirelesschannel and transmitting the demodulated and channel-decoded OFDM symbolto a higher layer.

In the next generation mobile communication system, a UE performsfrequency measurement while performing a cell selection or reselectionprocedure in an RRC idle mode or RRC inactive mode. The above frequencymeasurement performed while performing the cell selection or reselectionprocedure may refer to an intra-frequency measurement or a serving cellor Pcell measurement for frequencies set by a gNB or broadcasted in acamping cell. However, an inter-frequency measurement is not performedexcept the intra-frequency measurement or serving cell measurement, anda result of the frequency measurement is not separately reported to anetwork. However, when frequency measurement configuration informationof the RRC idle mode or RRC inactive mode is set in an RRC message(e.g., an RRCRelease message) by the gNB or received through systeminformation, or when supporting the frequency measurement configurationinformation of the RRC idle mode or RRC inactive mode is indicated inthe system information of the serving cell or camping cell, the UE mayalso perform the inter-frequency measurement procedure. If the UE hasstored a valid measurement result that satisfies a predeterminedcondition, the UE may quickly report the frequency measurement resultwhen establishing a connection with the network.

In addition, the UE may receive frequency measurement configurationinformation and perform a frequency measurement procedure even in an RRCconnected mode, as follows. The frequency measurement configurationinformation of the RRC connected mode may be set only in an RRC message(e.g., RRCReconfiguration message), whereas the frequency measurementconfiguration information of the RRC idle mode or RRC inactive mode maybe set to the UE through an RRC message (e.g., an RRCRelease message) orbroadcasted in system information. Particularly, in case of setting thefrequency measurement configuration information of the RRC idle mode orRRC inactive mode through the RRC message (unlike information set in thesystem information), a duration value or timer value specifying aduration for the UE to measure frequencies may be set, and areainformation (e.g., cell identifier list information for each frequency)specifying an area for the UE to measure frequencies may be set.

Also, the UE may receive the frequency measurement configurationinformation and perform the frequency measurement procedure even in theRRC connected mode, as follows. When the UE finds and camps on asuitable cell through a cell reselection procedure and then transitionsto the RRC connected mode through an RRC connection setup procedure, thegNB may set, to the RRC connected mode UE, which frequencies (e.g., afrequency list) or which frequency bands are to be measured, which orderis to be used for measurement through the priority setting for eachfrequency, which beam is to be measured, which filtering method is to beused for measuring frequency strength (e.g., an L1, L2, or L3 filteringmethod, or which calculation method and which coefficient are to be usedfor measurement), which event or condition is to be applied for startingthe frequency measurement, which criterion is to be used for thefrequency measurement in comparison with a current serving cell (or acurrently camping frequency), which event or condition is to be appliedfor reporting a result of the frequency measurement, which criterion orcondition needs to be satisfied for reporting the frequency incomparison with a current serving cell (or a currently campingfrequency), or which period is to be applied for reporting the frequencymeasurement result. The UE measures frequencies in accordance with theabove frequency configuration set by the gNB, and reports the frequencymeasurement result to the gNB in accordance with the corresponding eventor condition. Then, using the frequency measurement result received fromthe UE, the gNB may determine whether to apply the CA technology or theDC technology to the UE.

Disclosed herein is a method that the UE performs the frequencymeasurement in the RRC idle mode or RRC inactive mode beforetransitioning to the RRC connected mode in the next generation mobilecommunication system, the UE sends to the gNB an indicator indicatingthat there is a measurement result when establishing a connection withthe network, or the gNB requests the UE to report the measurementresult, and then the UE enters the RRC connected mode and quicklyreports the frequency measurement result. Accordingly, the gNB mayquickly configure the CA technology or the DC technology to the UE,based on the result of being measured by the UE in the RRC idle mode orRRC inactive mode.

Specifically, when enabling the RRC connected mode UE establishing theconnection with the network to transition to the RRC idle mode or RRCinactive mode, the gNB may set, to the UE through the RRC message,frequency information (or frequencies), time (or duration) information,and/or area information (or cell list) to be used for frequencymeasurement in the RRC idle mode or RRC inactive mode, and may alsoinstruct the UE to perform the frequency measurement in the RRC idlemode or RRC inactive mode. In addition, the UE may acquire systeminformation of a newly camping cell while performing a cell reselectionoperation whenever moving, and based on the system information, mayperform a procedure of continuing or terminating the frequencymeasurement in the RRC idle mode or RRC inactive mode, extending ameasurement duration (e.g., restarting a timer), reporting the frequencymeasurement result, discarding the frequency measurement result, orupdating the frequency configuration information.

In the disclosure, a bearer may include a signaling radio bearer (SRB)and a data radio bearer (DRB). In addition, a UM DRB indicates a DRBusing an RLC layer device operating in an unacknowledged mode (UM), andan AM DRB indicates a DRB using an RLC layer device operating in anacknowledged mode (AM).

FIG. 5 is a diagram illustrating a procedure of a terminal to transitionfrom an RRC idle mode or an RRC inactive mode to an RRC connected modeand configure a carrier aggregation technology in a next generationmobile communication system according to an embodiment of thedisclosure.

In FIG. 5, a base station (hereinafter, gNB) may transition a terminal(hereinafter, UE) of the RRC connected mode, which has established aconnection with a network, to the RRC idle mode or the RRC inactive modefor a predetermined reason. The predetermined reason may be a lack ofscheduling resources of the gNB or the suspension of datatransmission/reception with the UE for a predetermined time.

The gNB may transmit an RRCRelease message to the UE and therebyinstruct the UE to transition to the RRC idle mode or the RRC inactivemode (5-05). According to an embodiment, an indicator (suspend-config)contained in the RRCRelease message may instruct the UE to transition tothe RRC inactive mode, and if the indicator (suspend-config) is notcontained in the RRCRelease message, the UE may transition to the RRCidle mode.

The UE that transitions to the RRC idle mode or the RRC inactive modemay perform a random access procedure when a network connection isrequired for a predetermined reason, receive a random access response,request an RRC connection setup, receive an RRC message, and establishan RRC connection (5-10, 5-15, 5-20, 5-25, 5-30, 5-35, and 5-40).

The UE establishes backward transmission synchronization with the gNBthrough the random access procedure and transmits an RRCSetupRequestmessage to the gNB (5-25). The RRCSetupRequest message may contain anidentifier of the UE, a cause for establishing the connection(establishmentCause), and the like.

The gNB transmits an RRCSetup message so that the UE establishes the RRCconnection (5-30). The RRCSetup message may contain at least one ofconfiguration information for each logical channel, configurationinformation for each bearer, configuration information for a PDCP layerdevice, configuration information for an RLC layer device, andconfiguration information for a MAC layer device.

The RRCSetup message may allocate a bearer identifier (e.g., an SRBidentifier or a DRB identifier) to each bearer and indicateconfiguration of a PDCP layer device, an RLC layer device, a MAC layerdevice, and/or a PHY layer device for each bearer. In addition, theRRCConnectionSetup message may set a length (e.g., 12 bits or 18 bits)of a PDCP serial number used in the PDCP layer device for each bearer,and may set a length (e.g., 6 bits, 12 bits, or 18 bits) of an RLCserial number used in the RLC layer device. Also, the RRCConnectionSetupmessage may indicate whether to use header compression and decompressionprotocols in the uplink or downlink for each PDCP layer device for eachbearer, and may indicate whether to perform an integrity protection orverification procedure. Further, it may indicate whether to performout-of-order delivery in the PDCP layer device.

The UE establishing the RRC connection transmits an RRCSetupCompletemessage to the gNB (5-40). The RRCSetupComplete message may contain acontrol message, called SERVICE REQUEST, in which the UE requests abearer setup for a given service from AMF or MME. The gNB may transmitthe SERVICE REQUEST message contained in the RRCSetupComplete message tothe AMF or MME, and the AMF or MME may determine whether to provide theservice requested by the UE.

If determining to provide the UE-requesting service, the AMF or MMEtransmits a message called INITIAL CONTEXT SETUP REQUEST to the gNB. TheINITIAL CONTEXT SETUP REQUEST message may contain information such asquality of service (QoS) information to be applied to setting the DRB,and security-related information (e.g., security key, securityalgorithm) to be applied to the DRB.

The gNB transmits and receives a SecurityModeCommand message and aSecurityModeComplete message to and from the UE so as to establishsecurity, and when the security setting is completed, the gNB transmitsan RRCConnectionReconfiguration message to the UE (5-45).

The RRCConnectionReconfiguration message may allocate a beareridentifier (e.g., an SRB identifier or a DRB identifier) to each bearerand indicate configuration of a PDCP layer device, an RLC layer device,a MAC layer device, and/or a PHY layer device for each bearer. Inaddition, the RRCConnectionReconfiguration message may set a length(e.g., 12 bits or 18 bits) of a PDCP serial number used in the PDCPlayer device for each bearer, and may set a length (e.g., 6 bits, 12bits, or 18 bits) of an RLC serial number used in the RLC layer device.Also, the RRCConnectionSetup message may indicate whether to use headercompression and decompression protocols in the uplink or downlink foreach PDCP layer device for each bearer, and may indicate whether toperform an integrity protection or verification procedure. Further, itmay indicate whether to perform out-of-order delivery in the PDCP layerdevice.

In addition, the RRCConnectionReconfiguration message may containconfiguration information of the DRB for which user data is to beprocessed, and the UE sets the DRB by applying the above information andthen transmits an RRCConnectionReconfigurationComplete message to thegNB (5-50). The gNB completing the DRB setup with the UE may transmit anINITIAL CONTEXT SETUP COMPLETE message to the AMF or MME and therebycomplete the connection (5-50).

When the above process is completed, the UE transmits and receives datato and from the gNB through a core network (5-55 and 5-60). According tosome embodiments, the data transmission process is mainly composed ofthree operations: RRC connection setup, security setup, and DRB setup.In addition, for a certain reason, the gNB may transmit an RRCConnection Reconfiguration message to the UE so as to newly perform,add, or change setup (5-65).

The RRCConnectionReconfiguration message may contain frequencymeasurement configuration information (e.g., a list of frequencies to bemeasured, a duration of measuring a frequency, a condition of measuringa frequency, a condition of reporting a frequency after frequencymeasurement, a cell identifier for reporting a frequency, and/or thelike).

The UE performs frequency measurement in accordance with the frequencymeasurement configuration information, and may report a result of thefrequency measurement to the gNB (5-60) when a predetermined conditionis satisfied (e.g., if the signal strength of a specific frequency isbetter than a certain reference (e.g., a threshold value), or if thesignal strength of a current serving cell (frequency) is smaller than acertain reference (e.g., a threshold value)).

Upon receiving the frequency measurement result, the gNB may insertScell configuration information in the RRCReconfiguration message basedon the frequency measurement result (5-65) and transmit it to the UE toconfigure the carrier aggregation (CA) technology to the UE.Alternatively, the gNB may insert secondary cell group configurationinformation in the RRCReconfiguration message (5-65) and transmit it tothe UE to configure a dual connectivity (DC) technology to the UE.

In case of configuring the CA technology to the UE, the gNB maytransition Scells to an active, inactive, or idle state by using a MACcontrol element (MAC CE).

The procedure for the gNB to configure the CA technology or the DCtechnology to the UE may be summarized as follows. First, the UEestablishes a connection with the gNB, and the gNB sets frequencymeasurement configuration information to the RRC connected mode UE.Then, the UE performs frequency measurement based on the frequencymeasurement configuration information and reports a frequencymeasurement result to the gNB. In addition, the gNB may setconfiguration information for additional Scell, as an RRC message, toconfigure the CA technology to the UE based on the frequency measurementresult of the UE, and may enable such Scells to be active, idle, orinactive through MAC CE. Also, the gNB may set secondary cell groupconfiguration information to configure the DC technology to the UE basedon the frequency measurement result of the UE.

As described above, when the gNB configures the CA technology or the DCtechnology to the UE, the UE is required to enter the RRC connectedmode, receive the frequency measurement configuration information,perform the frequency measurement, and report the measurement result.Therefore, measurement reporting is performed very late, so that the CAtechnology or the DC technology is configured late. Accordingly, inorder to improve this issue, the disclosure proposes a method for the UEto efficiently perform the frequency measurement in the RRC idle mode orRRC inactive mode and report the frequency measurement result as soon asa connection with a network is established.

FIG. 6 is a diagram illustrating a first embodiment enabling a terminalto perform an early measurement in an RRC idle mode or an RRC inactivemode and make an early measurement report in a next generation mobilecommunication system according to an embodiment of the disclosure.

In the first embodiment of the disclosure, a base station (gNB) may seta plurality of frequency measurement groups when setting frequencymeasurement configuration information through the RRCRelease message orsystem information such that a terminal (UE) performs frequencymeasurement.

According to the first embodiment, the UE capable of performingfrequency measurement in the RRC idle mode or RRC inactive mode andquickly reporting a frequency measurement result may be the UEcorresponding to one or more of the following cases.

1. Any UE whose capability supports a method for early frequencymeasurement and early frequency measurement result report in the RRCidle mode or RRC inactive mode.

2. Among RRC idle mode or inactive mode UEs, any UE that receivesconfiguration information for instructing frequency measurement in theRRC idle mode or RRC inactive mode when the gNB transitions the UE fromthe RRC connected mode to the RRC idle mode or RRC inactive mode throughan RRC message. For example, any UE to which frequency configurationinformation, measurement duration (e.g., a timer value), or areaconfiguration information (e.g., a list of cell identifiers) for thefrequency measurement in the RRC idle mode or RRC inactive mode is set.

In FIG. 6, the UE in the RRC connection mode (6-05) may transition tothe RRC idle mode or RRC inactive mode (6-15) by the gNB for apredetermined reason (e.g., in case where there is no datatransmission/reception for a certain time). When transitioning the modeof the UE, the gNB may transmit an RRC message (6-10). For example, thegNB may transmit an RRCRelease message containing an indicator(suspend-config) instructing the UE to transition to the RRC inactivemode, or may transmit an RRCRelease message containing no indicator(suspend-config) to instruct the UE to transition to the RRC idle mode.The above RRC message (e.g., the RRCRelease message) may contain firstfrequency configuration information to be applied when the UE performsearly measurement in the RRC idle mode or RRC inactive mode. The firstfrequency configuration information may have information aboutfrequencies to be measured and a first timer value. The first timervalue may indicate a duration or a timer value (e.g., T331) forperforming frequency measurement in the RRC idle mode or RRC inactivemode. When the RRCRelease message instructs the frequency measurement inthe RRC idle mode or RRC inactive mode, the UE may perform the frequencymeasurement while a timer is running, and may stop the frequencymeasurement when the timer expires.

A condition for starting the frequency measurement when the UE performsthe early measurement in the RRC idle mode or RRC inactive mode mayinclude at least one of the following conditions (6-30).

1. If the received RRCRelease message contains an indicator to performfrequency measurement in the RRC idle mode or RRC inactive mode, and iffrequency information to be measured and a duration (e.g., a timervalue) for measuring frequencies are set, the UE may start a timer andperform frequency measurement according to the frequency information.

2. If the received RRCRelease message contains an indicator to performfrequency measurement in the RRC idle mode or RRC inactive mode, and ifonly a duration (e.g., a timer value) for measuring frequencies is setwithout frequency information, the UE may start a timer, perform a cellselection or reselection procedure, and acquire system information froma serving cell on which the UE camps (6-12). The system information maycontain second frequency configuration information to be applied whenthe UE performs the early measurement in the RRC idle mode or RRCinactive mode. If the frequency information to be measured in the RRCidle mode or RRC inactive mode is broadcasted in the system information,the UE may perform the frequency measurement according to the frequencyinformation. If new second frequency configuration information for theUE to measure in the RRC idle mode or RRC inactive mode is broadcastedin system information of another cell to and on which the UE moves andnewly camps, the UE may perform the frequency measurement in accordancewith the new second frequency configuration information.

As described above, the UE may start and perform the frequencymeasurement in the RRC idle mode or RRC inactive mode. If the UE movesto and camps on a new cell and acquires system information, and if theacquired system information has no indicator that frequency measurementis supported in the RRC idle mode or RRC inactive mode, the UE may stopthe frequency measurement while still operating a first timer. Aftermoving to another cell, if system information of that cell has anindicator that frequency measurement is supported in the RRC idle modeor RRC inactive mode, and if the first timer is still running, the UEmay restart the frequency measurement by using first frequencyconfiguration information, set in the RRCRelease message as suggestedabove, or second system information in the system information. In thesystem information, an indicator indicating LTE frequency measurementsupport and/or an indicator indicating NR frequency measurement supportmay be defined.

When one or more of the above conditions is/are satisfied, the UE maystart the early measurement in the RRC idle mode or RRC inactive mode.While performing the frequency measurement, the RRC idle mode or RRCinactive mode UE stores a valid measurement result that satisfies apredetermined condition. Based on the configuration information set inthe RRCRelease message or broadcasted in the system information, the UEmay determine whether or not the frequency measurement result that meetsthe predetermined condition is valid.

In addition, when it is necessary to establish a connection with thenetwork for data transmission and reception, the UE may transmit amessage 3 (e.g., an RRCSetupRequest or RRCResumeRequest message) to thegNB while performing a random access procedure (6-35), recognize thesuccess of the random access procedure by receiving a message 4 (e.g.,an RRCSetup or RRCResume message) from the gNB (6-40), and transition tothe RRC connected mode (6-45).

If system information (e.g., SIB2) received before the UE establishes aconnection in the current cell contains an indicator indicating thatfrequency measurement in the RRC idle mode or RRC inactive mode issupported, or an indicator indicating that a frequency measurementresult in the RRC idle mode or RRC inactive mode can be received, and ifthe UE has a valid frequency measurement result, the UE may transmit, tothe gNB, a message 5 (e.g., an RRCSetupComplete message or anRRCResumeComplete message) indicating that the UE has the frequencymeasurement result in the RRC idle mode or RRC inactive mode.

For example, when the UE has a valid frequency measurement result thatsatisfies a predetermined condition, the UE may transmit the message 5(e.g., RRC Setup Complete or RRC Resume Complete) that contains anindicator indicating that the early measurement has been performed inthe RRC idle mode or RRC inactive mode and there is a frequencymeasurement result to be reported. For this indicator contained in themessage 5, a new indicator for indicating that there is a earlyfrequency measurement result may be defined, or an indicator that hasalready defined in the RRC message (RRC Setup Complete or RRC ResumeComplete) to indicate that there is useful information in the UE may bereused (6-50). When the message 5 indicates having a frequencymeasurement result of the RRC idle mode or RRC inactive mode, anindicator for a measurement result for LTE frequencies and an indicatorfor a measurement result for NR frequencies may be respectively definedand indicated.

Upon recognizing, from the message 5, that the UE has performed theearly measurement in the RRC idle mode or RRC inactive mode and there isa measurement result to be reported, the gNB may transmit, to the UE, amessage requesting a measurement result report so as to quickly receivethe frequency measurement result (6-55). For example, the gNB may newlydefine a UEinformationRequest with a DL-DCCH message and, by using thismessage, request the frequency measurement result report from the UE.Upon receiving the message, the UE may report an early frequencymeasurement result to the gNB (6-65). For example, upon receiving themessage, the UE may newly define a UElnformationResponse message with aUL-DCCH message and, by using this message, report the frequencymeasurement result. The frequency measurement result may include ameasurement result of a serving cell/frequency (e.g., NR-SS RSRP/RSRQ),a measurement result of a neighboring cell/frequency around a servingcell/frequency, a measurement result of a neighboring cell/frequency theUE can measure, a measurement result of a cell/frequency instructed tomeasure, and/or the like. Alternatively, the gNB may define an indicatorin an RRCReconfiguration message and, by using it, request the frequencymeasurement result from the UE. Upon receiving the message, the UE mayreport the early frequency measurement result to the gNB (6-65). Forexample, upon receiving the message, the UE may report the frequencymeasurement result by using an RRCReconfigurationComplete message.Alternatively, the UE may define new fields for reporting the frequencymeasurement result in the UL-DCCH message and use them.

FIG. 7 is a diagram illustrating a second embodiment enabling a terminalto perform an early measurement in an RRC idle mode or an RRC inactivemode and make an early measurement report in a next generation mobilecommunication system according to an embodiment of the disclosure.

The above-described first embodiment may be applied at least in part tothe second embodiment of the disclosure, and the gNB may set, using anRRCRelease message, first frequency measurement configurationinformation to be applied when the UE performs frequency measurement inthe RRC idle mode or RRC inactive mode. Based on the first frequencyconfiguration information or the second frequency configurationinformation of the system information, the UE may perform frequencymeasurement in the RRC idle mode or RRC inactive mode. When the UEestablishes a connection with a network for data transmission andreception, the gNB may transmit an RRC message (e.g., an RRCResumemessage) containing an indicator requesting a frequency measurementresult to the UE. Upon receiving the indicator requesting the frequencymeasurement result, and upon having a valid frequency measurementresult, the UE may construct an RRC message (e.g., an RRCResumeCompletemessage) with the valid frequency measurement result and transmit themessage to the gNB to report the frequency measurement result.

In FIG. 7, when the RRC connected mode UE receives, from the gNB, thefirst frequency measurement configuration information together with aninstruction to release an RRC connection and transition to the RRC idlemode or RRC inactive mode, the UE may perform frequency measurement fora time or duration set above in the RRC idle mode or RRC inactive mode.In addition, when the second frequency measurement configurationinformation for frequency measurement of the RRC idle mode or RRCinactive mode UE is broadcasted in a cell on which the UE camps througha cell reselection procedure, the UE may receive the broadcastedinformation and perform the frequency measurement.

When the UE attempts to re-establish a connection with the network inthe RRC idle mode or RRC inactive mode, and when a cell for theconnection supports reporting an early frequency measurement result(e.g., when the system information has a related indicator), the UE mayperform a random access procedure, transmit a message 3 (e.g.,RRCResumeRequest), and receive from the gNB a message 4 (e.g., RRCResumemessage) containing an indicator requesting to report the frequencymeasurement result (7-40). Upon receiving the indicator to report thefrequency measurement result, and upon having a valid frequencymeasurement result, the UE may construct an RRC message (e.g., anRRCResumeComplete message) with the valid frequency measurement resultand transmit the message to the gNB to report the frequency measurementresult (7-50). Upon receiving the frequency measurement result, the gNBmay transmit CA technology configuration information or DC technologyconfiguration information when transmitting an RRC message (e.g., anRRCReconfiguration message) or MAC control information (MAC controlelement (MAC CE)) to the UE, thereby enabling the UE to quicklyreactivate, change, or newly set the CA technology or the DC technology(7-40). It is therefore possible to perform the frequency measurementresult reporting faster than in the first embodiment.

Meanwhile, disclosed hereinafter are details of the first frequencyconfiguration information, set in the RRCRelease message by the gNB, andthe second frequency configuration information broadcasted in the systeminformation such that in the first or second embodiment the UE can savethe battery and efficiently perform the frequency measurement procedurein the RRC idle mode or RRC inactive mode.

The first frequency configuration information, set in an RRC message(e.g., RRC connected mode frequency measurement is set in anRRCReconfiguration message, and RRC idle mode or RRC inactive modefrequency measurement is set in an RRCRelease message), may contain oneor more of a plurality of the following configuration information types.

-   -   A first target frequency list for the LTE frequency measurement    -   A first target SSB (synchronization signal block) frequency list        for the NR frequency measurement    -   A list (containing a cell identifier) of target cells to be        measured and reported for each frequency: When measuring the        frequency, the UE may measure only a signal corresponding to a        cell identifier contained in the cell list among cells operating        at the frequency. Then, if given conditions are met, the UE may        store a measurement result and report it to the network.    -   Threshold value information as a criterion to be measured and        reported for each frequency: If a signal having a cell        identifier contained in the cell list is measured with signal        strength higher than the threshold, the UE may regard it as a        valid measurement result, store it, and report the frequency        measurement result when connected to the network later.    -   First configuration information for SSB measurement for each        frequency: Auxiliary information that helps the UE to easily        perform SSB measurement for each frequency may be set, and may        include one or more of a plurality of configuration information        types as follows.        -   smtc (SSB block Measurement Time Configuration)            configuration information: Time configuration information            for SSB measurement of frequency, including duration,            offset, or periodicity in which the SSB is transmitted.        -   ssbSubcarrierSpacing configuration information: Information            including frequency interval for SSB measurement        -   ssb-ToMeasure configuration information: SSB identifier            information measured among SSBs        -   nrofSS-BlocksToAverage: Parameter information for deriving            cell signal strength        -   absThreshSS-BlocksConsolidation: Parameter information for            deriving cell signal strength    -   A first method for reporting frequency measurement for each        frequency (e.g., an RSRP, an RSRQ, a beam measurement result, a        beam identifier, a plurality of beam measurement results, or a        plurality of beam identifiers): The type of a measurement result        to be reported by the UE for each frequency or cell may be        instructed. For example, instructing to report RSRP or RSRQ,        instructing to report a beam measurement result as well,        instructing to report a beam identifier with valid signal        strength, or instructing to report a plurality of beam        measurement results or a plurality of beam identifiers with        valid signal strength may be possible. Further, it is possible        to instruct to report a measurement result or beam identifier of        a beam having the best signal strength.    -   First deriveSSB-IndexFromCell configuration information: If the        indicator is set to true when intra-frequency measurement is        performed, it means that when deriving SSB identifiers of SSB        blocks in smtc configuration information of other cells to be        measured in the frequency, timing of a current PCell or serving        cell is usable as a reference (reference timing). Therefore, the        UE can immediately know the SSB identifier of the frequency to        be measured without reading a physical broadcast channel (PBCH),        thereby saving UE power consumed in frequency measurement and        enabling early measurement. If the indicator is set to false,        the UE is required to synchronize with a cell of the frequency        to be measured and derive each SSB identifier by reading the        PBCH for SSB blocks. In addition, if the inter-frequency        measurement needs to be performed because of the frequency to be        measured, and if the indicator is set to true, this means that        if any cell of the frequency to be measured is synchronized, the        synchronized cell can be used as a reference timing when        performing SSB measurement for the other cells of the frequency,        and also means that an SSB identifier can be derived based on        the timing. If the indicator is false, the UE can perform        synchronization for each cell of the frequency and perform SSB        measurement.    -   First area configuration information: This is configuration        information for an area where the UE will perform frequency        measurement in the RRC idle mode or RRC inactive mode, and may        contain, for example, a cell list for each frequency (a list        containing cell identifiers).    -   First timer (e.g., valid timer) value or duration: This is a        timer indicating a duration during which the UE will perform        frequency measurement in the RRC idle mode or RRC inactive mode.        For example, when the first timer value or duration is set in        the RRCRelease message, the UE starts the first timer and        perform frequency measurement in the RRC idle mode or RRC        inactive mode, based on the frequency configuration information        set in the first frequency configuration information or the        second frequency configuration information. Upon receiving the        RRCSetup message or RRCResume message from the gNB when        establishing a connection with the network, the UE may consider        it as transitioning to the RRC connected mode and thereby stop        the first timer. Also, when going outside the first area (e.g.,        validity area), the UE may stop the first timer. If the first        timer is stopped, the UE may release the frequency configuration        information, stop the frequency measurement, and/or discard the        frequency measurement result.    -   Second timer value or duration: In order to confirm the validity        of the frequency measurement result, the gNB may set the second        timer value in the first frequency configuration information.        The second timer may be used to indicate a duration for        determining the validity of the frequency measurement result. It        may be determined that the stored frequency measurement result        value is valid only when the second timer is running. If the        second timer expires, the stored frequency measurement result        value may be discarded and not reported to the gNB. In addition,        the second timer may be driven for each UE, and when the first        timer indicating the frequency measurement duration expires or        when the frequency measurement is stopped, the second timer may        be started. When the second timer expires, the stored frequency        measurement results may be determined to be no longer valid and        thereby discarded. When the UE receives a request to report the        frequency measurement result from the gNB or the UE tries to        transmit the frequency measurement result to the gNB in an RRC        message while the second timer is running, the second timer may        be stopped. Also, the second timer may be driven for each        frequency or cell, and when the first timer indicating the        frequency measurement duration expires or when the frequency        measurement is stopped, the new timer may be started. In another        method, whenever the frequency measurement is performed for each        cell or frequency and then a new frequency measurement result is        stored for each cell or frequency, the second timer        corresponding to each cell or frequency may be started or        restarted. In addition, when the second timer expires, the        stored frequency measurement results for the cell or frequency        for which the second timer is running may be determined to be no        longer valid and discarded. Also, when the UE receives a request        to report the frequency measurement result from the gNB or the        UE tries to transmit the frequency measurement result to the gNB        in an RRC message while the second timer is running, the second        timer may be stopped.    -   Reference frequency or cell list for SSB measurement for each        frequency: This is configuration information for a frequency or        cells synchronized with a current gNB or frequency which is a        reference of timing when performing frequency measurement for a        frequency or cells set in a frequency list for LTE frequency        measurement or in a synchronization signal block (SSB) frequency        list for NR frequency measurement. The UE may synchronize with        one of frequencies or cells set in the reference frequency or        cell list when frequency measurement configuration is performed,        and then perform frequency measurement for other frequencies.

The second frequency configuration information set in the systeminformation proposed herein may contain one or more of a plurality ofthe following configuration information types. Unlike the firstfrequency configuration information, the second frequency configurationinformation may not include the first timer configuration information,the first area configuration information, or the second timerconfiguration information.

-   -   A second target frequency list for the LTE frequency measurement        (A frequency list for frequency measurement of the UE in the RRC        idle mode or RRC inactive mode or measurement configuration        information for neighboring cells or other frequencies useful        for determining camp-on when the UE selects or reselects a cell)    -   A second target SSB (synchronization signal block) frequency        list for the NR frequency measurement (A frequency list for        frequency measurement of the UE in the RRC idle mode or RRC        inactive mode or measurement configuration information for        neighboring cells or other frequencies useful for determining        camp-on when the UE selects or reselects a cell)    -   A list (containing a cell identifier) of target cells to be        measured and reported for each frequency: When measuring the        frequency, the UE may measure only a signal corresponding to a        cell identifier contained in the cell list among cells operating        at the frequency. Then, if given conditions are met, the UE may        store a measurement result and report it to the network.    -   Threshold value information as a criterion to be measured and        reported for each frequency: If a signal having a cell        identifier contained in the cell list is measured with signal        strength higher than the threshold, the UE may regard it as a        valid measurement result, store it, and report the frequency        measurement result when connected to the network later.    -   Second configuration information for SSB measurement for each        frequency: Auxiliary information that helps the UE to easily        perform SSB measurement for each frequency may be set, and may        include one or more of a plurality of configuration information        types as follows.        -   second smtc (SSB block Measurement Time Configuration)            configuration information: Time configuration information            for SSB measurement of frequency, including duration,            offset, or periodicity in which the SSB is transmitted.        -   ssbSubcarrierSpacing configuration information: Information            including frequency interval for SSB measurement        -   ssb-ToMeasure configuration information: SSB identifier            information measured among SSBs        -   nrofSS-BlocksToAverage: Parameter information for deriving            cell signal strength        -   absThreshSS-BlocksConsolidation: Parameter information for            deriving cell signal strength    -   A second method for reporting frequency measurement for each        frequency (e.g., an RSRP, an RSRQ, a beam measurement result, a        beam identifier, a plurality of beam measurement results, or a        plurality of beam identifiers): The type of a measurement result        to be reported by the UE for each frequency or cell may be        instructed. For example, instructing to report RSRP or RSRQ,        instructing to report a beam measurement result as well,        instructing to report a beam identifier with valid signal        strength, or instructing to report a plurality of beam        measurement results or a plurality of beam identifiers with        valid signal strength may be possible. Further, it is possible        to instruct to report a measurement result or beam identifier of        a beam having the best signal strength.    -   Second deriveSSB-IndexFromCell configuration information: If the        indicator is set to true when intra-frequency measurement is        performed, it means that when deriving SSB identifiers of SSB        blocks in smtc configuration information of other cells to be        measured in the frequency, timing of a current PCell or serving        cell is usable as a reference (reference timing). Therefore, the        UE can immediately know the SSB identifier of the frequency to        be measured without reading a physical broadcast channel (PBCH),        thereby saving UE power consumed in frequency measurement and        enabling early measurement. If the indicator is set to false,        the UE is required to synchronize with a cell of the frequency        to be measured and derive each SSB identifier by reading the        PBCH for SSB blocks. In addition, if the inter-frequency        measurement needs to be performed because of the frequency to be        measured, and if the indicator is set to true, this means that        if any cell of the frequency to be measured is synchronized, the        synchronized cell can be used as a reference timing when        performing SSB measurement for the other cells of the frequency,        and also means that an SSB identifier can be derived based on        the timing. If the indicator is false, the UE can perform        synchronization for each cell of the frequency and perform SSB        measurement.

FIG. 8 is a diagram illustrating a signal structure when a terminalperforms a frequency measurement for an LTE frequency in an RRC idlemode or an RRC inactive mode according to an embodiment of thedisclosure.

The LTE frequency may mean a frequency at which an LTE base station oran NR base station operates a cell with an LTE system, and a structureof a signal transmitted by the base station at the LTE frequency may beas shown in FIG. 8.

In FIG. 8, the base station may transmit a signal with a systembandwidth (BW) 8-05 for a first LTE frequency 8-10, and the UE has toread a signal according to the entire system bandwidth for the LTEfrequency. The signal of the LTE frequency uses subcarrier spacingdefined for all or most frequencies except for a broadcast service or aspecific service, such as MBMS, and an SSB having the same periodicity,duration, or offset is transmitted at a predetermined frequency position(e.g., six physical resource blocks (PRBs) in the middle of the systembandwidth). A channel reference signal (CRS) 8-20 may be uniformlytransmitted according to a predetermined rule.

The UE performing the RRC idle mode or RRC inactive mode frequencymeasurement proposed herein may first read a signal with thepredetermined system bandwidth for the LTE frequency when performingmeasurement for the LTE frequency, and then find the SSB signal at thepredetermined position. In addition, because the SSB signal usessubcarrier spacing defined for all or most frequencies and has the sameperiodicity, duration, or offset, the UE may quickly synchronize andfind the SSB signal. Then, based on the SSB signal, the UE may read amaster information block (MIB) signal and perform frequency measurementby measuring the CRS signal transmitted uniformly. Because the CRS isalways uniformly transmitted in the LTE frequency, the UE has anadvantage of quickly finding the CRS transmission resource andperforming early frequency measurement. Alternatively, the UE maymeasure the SSB signal of the LTE frequency and perform frequencymeasurement. Alternatively, an indicator set in the RRCRelease messageor the system information indicates, in case of the LTE frequency,whether to measure the SSB signal or the CRS signal, and the UE mayperform frequency measurement according to the indicator. In addition,when a predetermined condition set in the first frequency information orthe second frequency information is satisfied, a frequency measurementresult may be reported based on a predetermined method.

FIGS. 9 and 10 are diagrams each illustrating a signal structure when aterminal performs a frequency measurement for an NR frequency in an RRCidle mode or an RRC inactive mode according to an embodiment of thedisclosure.

The NR frequency may mean a frequency at which an NR base station or anLTE base station operates a cell with an NR system, and a structure of asignal transmitted by the base station at the NR frequency may be asshown in FIGS. 9 and 10.

In FIG. 9, the base station may transmit a signal with a systembandwidth (BW) 9-05 for a first NR frequency 9-01, and the UE may notread a signal according to the entire system bandwidth for the NRfrequency, but read a signal according to a partial bandwidth (BWP) 9-10or 9-20. In the NR system, the system bandwidth for each frequency isvery wide, so that if the UE reads all the system bandwidth, a largeamount of battery consumption may occur, and the base station operates aplurality of partial bandwidths for each frequency. Accordingly, the UEmay read a signal with a specific partial bandwidth (e.g., initialpartial bandwidth) for each frequency, find an SSB to synchronize, andmeasure a signal for the SSB. When operating the frequency, the basestation may use different subcarrier spacing for each partial bandwidthor for each frequency, and transmit SSBs having different periodicities,durations, or offsets at a predetermined frequency position (e.g., 12PRBs in the middle of the partial bandwidth). In addition, unlike theLTE frequency, the CRS 8-20 may not be transmitted. Because the basestation operates a plurality of partial bandwidths for the NR frequencyhaving a very wide bandwidth, CRS transmission may incur enormousoverhead for a signal transmitted by the base station. The SSB signalmay or may not be transmitted for each partial bandwidth among theplurality of partial bandwidths. However, for a specific partialbandwidth (e.g., initial partial bandwidth), the SSB signal is alwaystransmitted so that the RRC idle mode or RRC inactive mode UE cansynchronize a signal with the specific partial bandwidth, acquire systeminformation, and camp on.

As described above, in the NR frequency, different subcarrier spacingmay be used for each frequency. Also, because SSB signals havingdifferent periodicities, durations, or offsets are transmitted, the UEmay need to search the SSB signal for a long time to find the SSB signalfor each frequency and to find different periodicities, durations, oroffsets. As such, the UE needs to calculate the periodicity, duration,or offset of the SSB signal through complicated derivation, and thus,this procedure may cause a lot of battery consumption of the UE.

Therefore, as shown in FIG. 10, proposed in the disclosure is that smtcconfiguration information (or smtc configuration information or smtcinformation) for a frequency to be measured is set in first frequencyconfiguration information set with an RRC message or in the secondfrequency configuration information broadcasted with system informationsuch that the UE can easily perform frequency measurement. The smtcconfiguration information may contain an offset 10-21, duration 10-22,and/or periodicity 10-23 for the frequency to be measured, and areference timing for these parameters 10-21, 10-22, and 10-23 containedin the smtc configuration information may be based on a timing 10-05 ofa PCell or serving cell 10-01. For example, when the UE is configured toperform frequency measurement in the RRC connected, the UE may performfrequency measurement by applying the smtc information 10-21, 10-22, and10-23 based on the timing (e.g., system frame number (SFN) 0) 10-05 ofthe current PCell 10-01. In another example, when the UE is configuredto perform frequency measurement in the RRC idle mode or RRC inactivemode, the UE may perform frequency measurement by applying the smtcinformation 10-21, 10-22, and 10-23 based on the timing (e.g., SFN 0)10-05 of the serving cell 10-01 on which the UE currently camps.

A detailed procedure for the UE to perform the frequency measurementbased on the smtc information in the RRC connected mode is as follows.

-   -   Upon receiving the first frequency configuration information        with an RRC message from the base station in the RRC connected        mode, the UE prepares for frequency measurement for a frequency        or cell set in the first frequency configuration information.    -   When attempting to measure a specific frequency in the frequency        list set above, and when the smtc information is contained for        the frequency, the UE applies the smtc information based on the        timing of the PCell 10-01 to which a connection is currently        established. That is, the UE may measure an SSB signal in an SSB        signal transmission section by applying the offset 10-21 of the        smtc information based on the SFN 0 of the current PCell 10-01        and also applying the duration 10-22 of the smtc information,        and continuously measure an SSB signal at a time point of next        SSB signal transmission by applying the periodicity 10-23 of the        smtc information. Because the smtc information has been set for        the frequency, the UE can perform immediately frequency        measurement for the frequency, based on the smtc information and        the reference timing of the current PCell. As such, there is no        need to synchronize for the frequency, search for SSB signals        from the beginning, and derive parameter values of periodicity,        offset, and duration, so that it is possible to reduce battery        consumption of the UE and enable early frequency measurement.

A detailed procedure for the UE to perform the frequency measurementbased on the smtc information in the RRC idle mode or RRC inactive modeis as follows.

-   -   Upon receiving, in the RRC idle mode or RRC inactive mode, the        first frequency configuration information with an RRC message or        the second frequency configuration information with system        information of a serving cell on which the UE camps through a        cell selection or reselection procedure, the UE prepares for        frequency measurement for a frequency or cell set in the first        or second frequency configuration information.    -   When attempting to measure a specific frequency in the frequency        list set above, and when the smtc information is contained for        the frequency, the UE applies the smtc information based on the        timing of the serving cell 10-01 on which the UE camps through        the cell selection or reselection procedure in the RRC idle mode        or RRC inactive mode. That is, the UE may measure an SSB signal        in an SSB signal transmission section by applying the offset        10-21 of the smtc information based on the SFN 0 of the current        serving cell 10-01 and also applying the duration 10-22 of the        smtc information, and continuously measure an SSB signal at a        time point of next SSB signal transmission by applying the        periodicity 10-23 of the smtc information. Because the smtc        information has been set for the frequency, the UE can perform        immediately frequency measurement for the frequency, based on        the smtc information and the reference timing of the current        serving cell. As such, there is no need to synchronize for the        frequency, search for SSB signals from the beginning, and derive        parameter values of periodicity, offset, and duration, so that        it is possible to reduce battery consumption of the UE and        enable early frequency measurement.

The UE that performs frequency measurement in the RRC idle mode or RRCinactive mode is characterized by first finding the SSB signal for aspecific partial bandwidth (e.g., initial partial bandwidth) of the NRfrequency when performing measurement for the NR frequency. Because fordifferent frequencies the SSB signal may use different subcarrierspacings and have different periodicities, durations, and/or offsets,the UE may continuously search for the SSB signal and derive parametervalues of the periodicity, duration, and/or offset through calculation.Unlike measuring the CRS signal for the LTE frequency, for the NRfrequency the UE performs the frequency measurement for the SSB signalbased on the derived parameter values. In addition, when a predeterminedcondition set in the first or second frequency information is satisfied,the UE may report a frequency measurement result through a predeterminedmethod.

The method for performing the frequency measurement proposed for the LTEfrequency or the NR frequency may be extended and applied as a methodfor the UE to perform frequency measurement in the RRC idle mode, theRRC inactive mode, or the RRC connected mode.

In addition, when attempting to perform frequency measurement, the UEmay perform the frequency measurement using the method proposed in FIG.8 if the frequency to be measured is the LTE frequency, and also performthe frequency measurement using the method proposed in FIG. 9 or 10 ifthe frequency to be measured is the NR frequency.

FIG. 11 is a diagram illustrating a method for a terminal to perform afrequency measurement in an RRC idle mode or an RRC inactive mode in anetwork that is synchronized between different frequencies or cellsaccording to an embodiment of the disclosure.

In FIG. 11, the UE that transmits/receives data in the RRC connectedmode in a current cell 11-01 (first cell) may receive the RRCReleasemessage from the base station of the current cell 11-01, transition tothe RRC idle mode or RRC inactive mode, and move while performing thecell selection or reselection procedure. The RRCRelease message maycontain the first frequency configuration information. In addition, theRRC idle mode or RRC inactive mode UE may camp on a suitable cellthrough the cell selection or reselection procedure and acquire systeminformation. The UE may receive the second frequency configurationinformation in the system information.

If the received RRCRelease message contains the first frequencyconfiguration information, the UE may drive a timer by applying firsttimer value information of the first frequency configuration informationand start early frequency measurement of the RRC idle mode or RRCinactive mode. In addition, if the first frequency configurationinformation contains first area configuration information, the UE mayidentify an identifier of the camping cell and determine whether toperform the early frequency measurement of the RRC idle mode or RRCinactive mode.

If the UE is in a service area of the first cell 11-01, the UE mayperform the early frequency measurement of the RRC idle mode or RRCinactive mode, based on the first frequency configuration informationreceived in the RRCRelease message or the second frequency configurationinformation broadcasted as the system information by the first cell11-01. That is, when the UE attempts to measure a first frequency 11-10in the frequency list set above, and when the first frequencyconfiguration information received from the first cell contains firstsmtc configuration information or the second frequency configurationinformation received in the system information of the first cellcontains second smtc configuration information, the UE applies such smtcconfiguration information, based on timing of a serving cell (i.e., thefirst cell) 11-01 on which the UE camps through the cell selection orreselection procedure in the RRC idle mode or RRC inactive mode. Thatis, the UE may measure an SSB signal in an SSB signal transmissionsection by applying the offset of the smtc information based on the SFN0 of the current serving cell 11-01 and also applying the duration ofthe smtc information, and continuously measure an SSB signal at a timepoint of next SSB signal transmission by applying the periodicity of thesmtc information. Because the smtc information has been set for thefrequency, the UE can perform immediately frequency measurement for thefrequency, based on the smtc information and the reference timing of thecurrent serving cell. As such, there is no need to synchronize for thefrequency, search for SSB signals from the beginning, and deriveparameter values of periodicity, offset, and duration, so that it ispossible to reduce battery consumption of the UE and enable earlyfrequency measurement. If the smtc configuration information is notcontained for the frequency, the UE may not perform the RRC idle mode orRRC inactive mode frequency measurement for the frequency to reducebattery consumption. Alternatively, even when there is no smtcconfiguration information, the UE may perform the RRC idle mode or RRCinactive mode frequency measurement by being implemented to synchronizefor the frequency, search for SSB signals from the beginning, and deriveparameter values of periodicity, offset, and duration.

If the UE moves from the first cell 11-01 to a service area of a secondcell 11-02 and camps on the second cell 11-02, the UE may perform theRRC idle mode or RRC inactive mode frequency measurement based on thefirst frequency configuration information received in the RRCReleasemessage or the second frequency configuration information broadcasted asthe system information by the second cell 11-02. That is, when the UEattempts to measure a second frequency 11-20 in the frequency list setabove, and when the first frequency configuration information receivedfrom the first cell contains first smtc configuration information or thesecond frequency configuration information received in the systeminformation of the second cell contains second smtc configurationinformation, the UE applies such smtc configuration information, basedon timing of a serving cell (i.e., the second cell) 11-02 on which theUE camps through the cell selection or reselection procedure in the RRCidle mode or RRC inactive mode. That is, the UE may measure an SSBsignal in an SSB signal transmission section by applying the offset ofthe smtc information based on the SFN 0 of the current serving cell11-02 and also applying the duration of the smtc information, andcontinuously measure an SSB signal at a time point of next SSB signaltransmission by applying the periodicity of the smtc information.Because the smtc information has been set for the frequency, the UE canperform immediately frequency measurement for the frequency, based onthe smtc information and the reference timing of the current servingcell. As such, there is no need to synchronize for the frequency, searchfor SSB signals from the beginning, and derive parameter values ofperiodicity, offset, and duration, so that it is possible to reducebattery consumption of the UE and enable early frequency measurement. Ifthe smtc configuration information is not contained for the frequency,the UE may not perform the RRC idle mode or RRC inactive mode frequencymeasurement for the frequency to reduce battery consumption.Alternatively, even when there is no smtc configuration information, theUE may perform the RRC idle mode or RRC inactive mode frequencymeasurement by being implemented to synchronize for the frequency,search for SSB signals from the beginning, and derive parameter valuesof periodicity, offset, and duration.

FIG. 12 is a diagram illustrating a problem that occurs when a terminalperforms a frequency measurement in an RRC idle mode or an RRC inactivemode in a network that is not synchronized between different frequenciesor cells according to an embodiment of the disclosure.

In FIG. 12, the UE that transmits/receives data in the RRC connectedmode in a current cell 12-01 (first cell) may receive the RRCReleasemessage from the base station of the current cell 12-01, transition tothe RRC idle mode or RRC inactive mode, and move while performing thecell selection or reselection procedure. The RRCRelease message maycontain the first frequency configuration information. In addition, theRRC idle mode or RRC inactive mode UE may camp on a suitable cellthrough the cell selection or reselection procedure and acquire systeminformation. The UE may receive the second frequency configurationinformation in the system information.

If the received RRCRelease message contains the first frequencyconfiguration information, the UE may drive a timer by applying firsttimer value information of the first frequency configuration informationand start early frequency measurement of the RRC idle mode or RRCinactive mode. In addition, if the first frequency configurationinformation contains first area configuration information, the UE mayidentify an identifier of the camping cell and determine whether toperform the early frequency measurement of the RRC idle mode or RRCinactive mode.

If the UE is in a service area of the first cell 12-01, the UE mayperform the early frequency measurement of the RRC idle mode or RRCinactive mode, based on the first frequency configuration informationreceived in the RRCRelease message or the second frequency configurationinformation broadcasted as the system information by the first cell12-01. That is, when the UE attempts to measure a first frequency 12-10in the frequency list set above, and when the first frequencyconfiguration information received from the first cell contains firstsmtc configuration information or the second frequency configurationinformation received in the system information of the first cellcontains second smtc configuration information, the UE applies such smtcconfiguration information, based on timing of a serving cell (i.e., thefirst cell) 12-01 on which the UE camps through the cell selection orreselection procedure in the RRC idle mode or RRC inactive mode. Thatis, the UE may measure an SSB signal in an SSB signal transmissionsection by applying the offset of the smtc information based on the SFN0 of the current serving cell 12-01 and also applying the duration ofthe smtc information, and continuously measure an SSB signal at a timepoint of next SSB signal transmission by applying the periodicity of thesmtc information. Because the smtc information has been set for thefrequency, the UE can perform immediately frequency measurement for thefrequency, based on the smtc information and the reference timing of thecurrent serving cell. As such, there is no need to synchronize for thefrequency, search for SSB signals from the beginning, and deriveparameter values of periodicity, offset, and duration, so that it ispossible to reduce battery consumption of the UE and enable earlyfrequency measurement. If the smtc configuration information is notcontained for the frequency, the UE may not perform the RRC idle mode orRRC inactive mode frequency measurement for the frequency to reducebattery consumption. Alternatively, even when there is no smtcconfiguration information, the UE may perform the RRC idle mode or RRCinactive mode frequency measurement by being implemented to synchronizefor the frequency, search for SSB signals from the beginning, and deriveparameter values of periodicity, offset, and duration.

If the UE moves from the first cell 12-01 to a service area of a secondcell 12-02 and camps on the second cell 12-02, the UE may perform theRRC idle mode or RRC inactive mode frequency measurement based on thefirst frequency configuration information received in the RRCReleasemessage or the second frequency configuration information broadcasted asthe system information by the second cell 12-02. That is, when the UEattempts to measure a second frequency 12-20 in the frequency list setabove, and when the first frequency configuration information receivedfrom the first cell contains first smtc configuration information or thesecond frequency configuration information received in the systeminformation of the second cell contains second smtc configurationinformation, the UE applies such smtc configuration information, basedon timing of a serving cell (i.e., the second cell) 12-02 on which theUE camps through the cell selection or reselection procedure in the RRCidle mode or RRC inactive mode. That is, the UE may measure an SSBsignal in an SSB signal transmission section by applying the offset ofthe smtc information based on the SFN 0 of the current serving cell12-02 and also applying the duration of the smtc information, andcontinuously measure an SSB signal at a time point of next SSB signaltransmission by applying the periodicity of the smtc information.

However, in FIG. 12, the time synchronization between the first cell12-01 and the second cell 12-02 does not match. Thus, if applying thefirst smtc information for the second frequency 12-20, contained in thefirst frequency configuration information received in the RRCReleasemessage of the first cell, when measuring the second frequency 12-20 inthe second cell, a problem that the frequency measurement is impossibledue to asynchronous timing may occur. This is because the first smtcinformation for the second frequency 12-20 contained in the firstfrequency configuration information received in the RRCRelease messageof the first cell is information set based on the reference timing ofthe first cell. If the UE applies the first smtc information, based onthe reference timing of the second cell, in the area of the second cell,a section of the frequency measurement will not match as much as a gapbetween the timing of the first cell and the timing of the second cell.Therefore, the UE may not normally perform the RRC idle mode or RRCinactive mode frequency measurement for the second frequency.

Described hereinafter is a method for an efficient RRC idle mode or RRCinactive mode frequency measurement that can solve the above problem offrequency measurement failure due to asynchronous timing in FIG. 12 andminimize battery consumption of the UE.

FIG. 13 is a diagram illustrating a first embodiment of an efficientfrequency measurement method in an RRC idle mode or an RRC inactive modeaccording to an embodiment of the disclosure.

In FIG. 13, the base station or cell may set configuration informationfor the RRC idle mode or RRC inactive mode frequency measurement to theUE by using first frequency measurement configuration information 13-10in the RRCRelease message or second frequency measurement configurationinformation 13-20 in the system information.

If the received RRCRelease message contains the first frequencyconfiguration information, the UE may drive a timer by applying firsttimer value information of the first frequency configuration informationand start the RRC idle mode or RRC inactive mode frequency measurement(i.e., early measurement). In addition, if the first frequencyconfiguration information contains first area configuration information,the UE may identify an identifier of a cell on which the UE campsthrough the cell selection or reselection procedure, and may determinewhether to perform the early frequency measurement of the RRC idle modeor RRC inactive mode. If the first frequency configuration informationdoes not contain first frequency list information to be measured, and ifthe second frequency configuration is broadcasted in the systeminformation of the camping cell, the UE may perform the RRC idle mode orRRC inactive mode frequency measurement, based on the second frequencyconfiguration information (e.g., second frequency list information),store a valid measurement result, and report the stored measurementresult to the network as described in FIG. 6 or 7 when establishing anRRC connection later.

In the first embodiment of the efficient RRC idle mode or RRC inactivemode frequency measurement method as shown in FIG. 13, the UE mayreceive the first frequency configuration information through theRRCRelease message, transition to the RRC idle mode or RRC inactivemode, and perform the frequency measurement. In addition, the UE mayreceive the second frequency configuration information through thesystem information of a cell on which the UE camps through the cellselection or reselection procedure.

The first embodiment is characterized in that the UE receives the firstfrequency configuration information and/or the second frequencyconfiguration information, prioritizes the first frequency configurationinformation when performing the RRC idle mode or RRC inactive modefrequency measurement, and performs the frequency measurement based onthe first frequency configuration information only. In addition, the UEmay perform the frequency measurement in consideration of the secondfrequency configuration information with respect to configurationinformation that is not contained in the first frequency configurationinformation.

For example, the UE may receive the first frequency configurationinformation in the RRCRelease message 13-10 from the first cell,transition to the RRC idle mode or RRC inactive mode, and then receivethe second frequency configuration information in the system information13-20 from the first cell or a new second cell through the cellselection or reselection procedure.

A first frequency list of the first frequency configuration information13-10 may contain, as target frequencies to be measured, frequency 1(13-01), frequency 2 (13-02), frequency 3 (13-03), frequency 4 (13-04),frequency 5 (13-05), and frequency 6 (13-06). Among these frequencies,only frequency 1 (13-01), frequency 2 (13-02), frequency 3 (13-03), andfrequency 5 (13-05) may be configured with threshold value informationused as a criterion for measurement and report for each frequency, firstconfiguration information for SSB measurement for each frequency, or afirst reporting method for measurement report for each frequency.

A second frequency list of the second frequency configurationinformation 13-20 may contain, as target frequencies to be measured,frequency 3 (13-03), frequency 4 (13-04), frequency 5 (13-05), frequency6 (13-06), frequency 7 (13-07), and frequency 8 (13-08). Among thesefrequencies, only frequency 3 (13-03), frequency 4 (13-04), frequency 7(13-07), and frequency 8 (13-08) may be configured with threshold valueinformation used as a criterion for measurement and report for eachfrequency, second configuration information for SSB measurement for eachfrequency, or a second reporting method for measurement report for eachfrequency.

Upon receiving the first frequency configuration information 13-10 orthe second frequency configuration information 13-20, the UE may selectfrequencies to be measured, and then apply one of the following methodsso as to determine frequency configurations to be applied to therespective frequencies.

-   -   Method 1-1 (13-51): The UE prioritizes the first frequency        configuration information 13-10 to perform frequency        measurement. Therefore, the UE may perform the frequency        measurement only for frequencies 13-51 (i.e., frequency 1        (13-01), frequency 2 (13-02), frequency 3 (13-03), frequency 4        (13-04), frequency 5 (13-05), and frequency 6 (13-06)) set in        the first frequency list by applying frequency measurement        configuration information for each frequency (e.g., the        threshold value information used as a criterion for measurement        and report for each frequency, the first configuration        information for SSB measurement for each frequency, or the first        reporting method for measurement report for each frequency) set        in the first frequency configuration information 13-10,        determine a valid frequency measurement result, construct a        result to be reported, and store the constructed result.        Specifically, in the method 1-1, the UE may perform the        frequency measurement by applying first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency, based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is no first        configuration information for SSB measurement for a target        frequency to be measured, the UE may not perform the measurement        for the frequency to reduce battery consumption. In one        alternative method, even when there is no first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency, the UE may perform the        RRC idle mode or RRC inactive mode frequency measurement by        being implemented to synchronize for the frequency, search for        SSB signals from the beginning, and derive parameter values of        periodicity, offset, and duration. In another alternative        method, the UE may store a reference timing of a cell from which        the RRCRelease message is received, and perform the measurement        by applying the first configuration information for SSB        measurement for each frequency, based on the stored timing. In        such method 1-1, the UE performs the frequency measurement based        on the first frequency configuration information only, so that        it is not necessary to read a lot of system information, thereby        reducing the battery consumption of the UE.    -   Method 1-2 (13-52): The UE prioritizes the first frequency        configuration information 13-10 to perform frequency        measurement. Therefore, the UE may perform the frequency        measurement only for frequencies 13-52 (i.e., frequency 1        (13-01), frequency 2 (13-02), frequency 3 (13-03), frequency 4        (13-04), frequency 5 (13-05), and frequency 6 (13-06)) set in        the first frequency list by applying frequency measurement        configuration information for each frequency (e.g., the        threshold value information used as a criterion for measurement        and report for each frequency, the first configuration        information for SSB measurement for each frequency, or the first        reporting method for measurement report for each frequency) set        in the first frequency configuration information 13-10,        determine a valid frequency measurement result, construct a        result to be reported, and store the constructed result.        Specifically, in the method 1-2, the UE may perform the        frequency measurement by applying first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency, based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is no first        configuration information for SSB measurement for a target        frequency (e.g., frequency 4 (13-04)) to be measured, but if the        second frequency configuration information received in the        system information contains second configuration information for        SSB measurement for the frequency, the UE may perform the        frequency measurement by applying the second configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency (e.g., frequency 4        (13-04)), based on a reference timing of a serving cell on which        the UE camps through the cell selection or reselection        procedure. If there is neither first configuration information        nor second configuration information for SSB measurement for a        target frequency to be measured, the UE may not perform the        measurement for the frequency to reduce battery consumption. In        one alternative method, even if there is no first configuration        information for SSB measurement for each frequency, or even if        there is no second configuration information for SSB measurement        for each frequency, the UE may perform the RRC idle mode or RRC        inactive mode frequency measurement by being implemented to        synchronize for the frequency, search for SSB signals from the        beginning, and derive parameter values of periodicity, offset,        and duration. In another alternative method, the UE may store a        reference timing of a cell from which the RRCRelease message is        received, and perform the measurement by applying the first        configuration information or second configuration information        for SSB measurement for each frequency, based on the stored        timing.

One variation of the first embodiment for the efficient RRC idle mode orRRC inactive mode frequency measurement method is as follows.

In FIG. 13, the base station or cell may set configuration informationfor the RRC idle mode or RRC inactive mode frequency measurement to theUE by using first frequency measurement configuration information 13-10in the RRCRelease message or second frequency measurement configurationinformation 13-20 in the system information.

If the received RRCRelease message contains the first frequencyconfiguration information, the UE may drive a timer by applying firsttimer value information of the first frequency configuration informationand start the RRC idle mode or RRC inactive mode frequency measurement(i.e., early measurement). In addition, if the first frequencyconfiguration information contains first area configuration information,the UE may identify an identifier of a cell on which the UE campsthrough the cell selection or reselection procedure, and may determinewhether to perform the early frequency measurement of the RRC idle modeor RRC inactive mode. If the first frequency configuration informationdoes not contain first frequency list information to be measured, and ifthe second frequency configuration is broadcasted in the systeminformation of the camping cell, the UE may perform the RRC idle mode orRRC inactive mode frequency measurement, based on the second frequencyconfiguration information (e.g., second frequency list information),store a valid measurement result, and report the stored measurementresult to the network as described in FIG. 6 or 7 when establishing anRRC connection later.

In one variation of the first embodiment for the efficient RRC idle modeor RRC inactive mode frequency measurement method, the UE may receivethe first frequency configuration information through the RRCReleasemessage, transition to the RRC idle mode or RRC inactive mode, andperform the frequency measurement. In addition, the UE may receive thesecond frequency configuration information through the systeminformation of a cell on which the UE camps through the cell selectionor reselection procedure.

One variation of the first embodiment is characterized in that the UEreceives the first frequency configuration information and/or the secondfrequency configuration information and in that, when performing the RRCidle mode or RRC inactive mode frequency measurement, the UE alwaysprioritizes the first frequency list information than the secondfrequency list information in case of receiving both the first frequencyconfiguration information and the second frequency configurationinformation, but prioritizes the second configuration information forSSB measurement for each frequency in case of receiving both the firstconfiguration information for SSB measurement for each frequency and thesecond configuration information for SSB measurement for each frequency.However, if a cell from which the UE receives the system information isidentical with a cell from which the UE receives the RRCRelease message,and if, for a specific frequency in the first frequency list, the UEreceives the first configuration information for SSB measurement throughRRCRelease message and receives the second configuration information forSSB measurement through the system information of the same cell, the UEmay apply the first configuration information for SSB measurement foreach frequency in the first frequency list. This is because if differentkinds of information are received from the same cell through theRRCRelease message and the system information, the UE should givepriority to specific information (dedicated to the UE) directly providedby the base station. In the case of certain UE that does not have muchmobility and continuously camps on the same cell, the firstconfiguration information for SSB measurement for each frequency may bemore efficient for frequency measurement for the CA technology or DCtechnology.

If the RRCRelease message contains only the first frequency list withoutthe first configuration information for SSB measurement for eachfrequency, and if the second configuration information for SSBmeasurement for each frequency contained in the first frequency list isbroadcasted through the system information, the UE may perform thefrequency measurement by applying the second configuration informationfor SSB measurement for each frequency to frequencies of the firstfrequency list.

For example, the UE may receive the first frequency configurationinformation in the RRCRelease message 13-10 from the first cell,transition to the RRC idle mode or RRC inactive mode, and then receivethe second frequency configuration information in the system information13-20 from the first cell or a new second cell through the cellselection or reselection procedure.

A first frequency list of the first frequency configuration information13-10 may contain, as target frequencies to be measured, frequency 1(13-01), frequency 2 (13-02), frequency 3 (13-03), frequency 4 (13-04),frequency 5 (13-05), and frequency 6 (13-06). Among these frequencies,only frequency 1 (13-01), frequency 2 (13-02), frequency 3 (13-03), andfrequency 5 (13-05) may be configured with threshold value informationused as a criterion for measurement and report for each frequency, firstconfiguration information for SSB measurement for each frequency, or afirst reporting method for measurement report for each frequency.

A second frequency list of the second frequency configurationinformation 13-20 may contain, as target frequencies to be measured,frequency 3 (13-03), frequency 4 (13-04), frequency 5 (13-05), frequency6 (13-06), frequency 7 (13-07), and frequency 8 (13-08). Among thesefrequencies, only frequency 3 (13-03), frequency 4 (13-04), frequency 7(13-07), and frequency 8 (13-08) may be configured with threshold valueinformation used as a criterion for measurement and report for eachfrequency, second configuration information for SSB measurement for eachfrequency, or a second reporting method for measurement report for eachfrequency.

Upon receiving the first frequency configuration information 13-10 orthe second frequency configuration information 13-20, the UE may selectfrequencies to be measured, and then apply one of the following methodsso as to determine frequency configurations to be applied to therespective frequencies.

-   -   Method 1-1-1 (13-51):        -   1> If the UE moves within the first cell, from which the            RRCRelease message has been received, and camps on the same            first cell again (13-52),        -   2> The UE prioritizes the first frequency configuration            information 13-10 to perform frequency measurement.            Therefore, the UE may perform the frequency measurement for            frequencies 13-51 (i.e., frequency 1 (13-01), frequency 2            (13-02), frequency 3 (13-03), frequency 4 (13-04), frequency            5 (13-05), and frequency 6 (13-06)) set in the first            frequency list by applying frequency measurement            configuration information for each frequency (e.g., the            threshold value information used as a criterion for            measurement and report for each frequency, the first            configuration information for SSB measurement for each            frequency, or the first reporting method for measurement            report for each frequency) set in the first frequency            configuration information 13-10, determine a valid frequency            measurement result, construct a result to be reported, and            store the constructed result. That is, even if the second            configuration information for SSB measurement for each            frequency corresponding to the first frequency list is            broadcasted in the system information, the UE may prioritize            information of the RRCRelease message because the RRCRelease            message is received from the same cell. Specifically, in the            method 1-1-1, the UE may perform the frequency measurement            by applying the first configuration information (e.g.,            periodicity, offset, and/or duration of smtc) for SSB            measurement for a target frequency (e.g., frequency 4            (13-04)) to be measured, based on a reference timing of a            serving cell on which the UE camps through the cell            selection or reselection procedure. In one alternative            method, the UE may store a reference timing of the cell from            which the RRCRelease message is received, and perform the            measurement by applying the first configuration information            or second configuration information for SSB measurement for            each frequency, based on the stored timing. If there is            neither first configuration information nor second            configuration information for SSB measurement for a target            frequency to be measured, the UE may not perform the            measurement for the frequency to reduce battery consumption.            In another alternative method, even if there is no first            configuration information for SSB measurement for each            frequency, or even if there is no second configuration            information for SSB measurement for each frequency, the UE            may perform the RRC idle mode or RRC inactive mode frequency            measurement by being implemented to synchronize for the            frequency, search for SSB signals from the beginning, and            derive parameter values of periodicity, offset, and            duration. In still another alternative method, if there is            no first configuration information for SSB measurement for a            target frequency (e.g., frequency 4 (13-04)) to be measured,            but if the second frequency configuration information            received in the system information contains second            configuration information for SSB measurement for the            frequency, the UE may perform the frequency measurement by            applying the second configuration information (e.g.,            periodicity, offset, and/or duration of smtc) for SSB            measurement for the frequency, based on a reference timing            of a serving cell on which the UE camps through the cell            selection or reselection procedure.        -   2> If the first frequency configuration information received            in the RRCRelease message does not contain the configuration            information for the first frequency list, the UE may apply a            method 2-1 (14-51) to be described below. Specifically, the            UE prioritizes the second frequency configuration            information 14-20 to perform frequency measurement.            Therefore, the UE may perform the frequency measurement only            for frequencies 14-51 (i.e., frequency 3 (14-03), frequency            4 (14-04), frequency 5 (14-05), frequency 6 (14-06),            frequency 7 (14-07), and frequency 8 (14-08)) set in the            second frequency list by applying frequency measurement            configuration information for each frequency (e.g., the            threshold value information used as a criterion for            measurement and report for each frequency, the second            configuration information for SSB measurement for each            frequency, or the second reporting method for measurement            report for each frequency) set in the second frequency            configuration information 14-20, determine a valid frequency            measurement result, construct a result to be reported, and            store the constructed result. Specifically, in the method            2-1, the UE may perform the frequency measurement by            applying the second configuration information (e.g.,            periodicity, offset, and/or duration of smtc) for SSB            measurement for a target frequency to be measured, based on            a reference timing of a serving cell on which the UE camps            through the cell selection or reselection procedure. If            there is no second configuration information for SSB            measurement for a target frequency to be measured, the UE            may not perform the measurement for the frequency to reduce            battery consumption. In one alternative method, even when            there is no second configuration information for SSB            measurement for each frequency, the UE may perform the RRC            idle mode or RRC inactive mode frequency measurement by            being implemented to synchronize for the frequency, search            for SSB signals from the beginning, and derive parameter            values of periodicity, offset, and duration. In another            alternative method, the method 2-2 (14-52) may be applied.        -   1> If the UE moves from the first cell, from which the            RRCRelease message has been received, and camps on a new            second cell (13-53),        -   2> The UE prioritizes the first frequency list of the first            frequency configuration information 13-10 to perform            frequency measurement. However, when performing measurements            of frequencies of the first frequency list, it may be            characterized in that preference is given to the second            configuration information for SSB measurement for each            frequency rather than the first configuration information            for SSB measurement for each frequency. Therefore, the UE            may perform the frequency measurement for frequencies 13-51            (i.e., frequency 1 (13-01), frequency 2 (13-02), frequency 3            (13-03), frequency 4 (13-04), frequency 5 (13-05), and            frequency 6 (13-06)) set in the first frequency list by            applying frequency measurement configuration information for            each frequency (e.g., the threshold value information used            as a criterion for measurement and report for each            frequency, the first configuration information for SSB            measurement for each frequency, or the first reporting            method for measurement report for each frequency) set in the            first frequency configuration information 13-10, determine a            valid frequency measurement result, construct a result to be            reported, and store the constructed result. Specifically, if            the first configuration information for SSB measurement for            a target frequency corresponding to the first frequency list            is received, but if the second configuration information for            SSB measurement for the frequency is broadcasted in the            system information from in a new second cell, the UE may            prioritize the second configuration information for SSB            measurement for each frequency broadcasted in the system            information to perform frequency measurement. That is, in            the method 1-1-1, the UE may perform the frequency            measurement by applying the second configuration information            (e.g., periodicity, offset, and/or duration of smtc) for SSB            measurement for a target frequency (e.g., frequency 4            (13-04)) to be measured, based on a reference timing of a            serving cell on which the UE camps through the cell            selection or reselection procedure. This is because, if the            UE moves and camps on the new second cell, the second            configuration information for SSB measurement for each            frequency broadcasted from the new second cell is likely to            be more accurate than the first configuration information            for SSB measurement for each frequency received from the            previous first cell. In addition, it is because, if cell            synchronization does not match in the base station            implementation, following the system information of the new            second cell may not cause a problem due to asynchronous            timing between cells. If there is neither first            configuration information nor second configuration            information for SSB measurement for a target frequency to be            measured, the UE may not perform the measurement for the            frequency to reduce battery consumption. In one alternative            method, even if there is no first configuration information            for SSB measurement for each frequency, or even if there is            no second configuration information for SSB measurement for            each frequency, the UE may perform the RRC idle mode or RRC            inactive mode frequency measurement by being implemented to            synchronize for the frequency, search for SSB signals from            the beginning, and derive parameter values of periodicity,            offset, and duration. In another alternative method, if the            second configuration information for SSB measurement for            each frequency is not broadcasted in the system information            for a target frequency of the first frequency list to be            measured, but if the first frequency configuration            information received in the RRCRelease message contains the            first configuration information for SSB measurement for the            frequency, the UE may perform the frequency measurement by            applying the first configuration information (e.g.,            periodicity, offset, and/or duration of smtc) for SSB            measurement for the frequency, based on a reference timing            of a serving cell on which the UE camps through the cell            selection or reselection procedure. In still another            alternative method, the UE may store a reference timing of            the cell from which the RRCRelease message is received, and            perform the measurement by applying the first configuration            information or second configuration information for SSB            measurement for each frequency, based on the stored timing.            In yet another alternative method, the method 1-1 or the            method 1-2, described above, may be applied.        -   2> If the first frequency configuration information received            in the RRCRelease message does not contain the configuration            information for the first frequency list, the UE may apply a            method 2-1 (14-51) to be described below. Specifically, the            UE prioritizes the second frequency configuration            information 14-20 to perform frequency measurement.            Therefore, the UE may perform the frequency measurement only            for frequencies 14-51 (i.e., frequency 3 (14-03), frequency            4 (14-04), frequency 5 (14-05), frequency 6 (14-06),            frequency 7 (14-07), and frequency 8 (14-08)) set in the            second frequency list by applying frequency measurement            configuration information for each frequency (e.g., the            threshold value information used as a criterion for            measurement and report for each frequency, the second            configuration information for SSB measurement for each            frequency, or the second reporting method for measurement            report for each frequency) set in the second frequency            configuration information 14-20, determine a valid frequency            measurement result, construct a result to be reported, and            store the constructed result. Specifically, in the method            2-1, the UE may perform the frequency measurement by            applying the second configuration information (e.g.,            periodicity, offset, and/or duration of smtc) for SSB            measurement for a target frequency to be measured, based on            a reference timing of a serving cell on which the UE camps            through the cell selection or reselection procedure. If            there is no second configuration information for SSB            measurement for a target frequency to be measured, the UE            may not perform the measurement for the frequency to reduce            battery consumption. In one alternative method, even when            there is no second configuration information for SSB            measurement for each frequency, the UE may perform the RRC            idle mode or RRC inactive mode frequency measurement by            being implemented to synchronize for the frequency, search            for SSB signals from the beginning, and derive parameter            values of periodicity, offset, and duration. In another            alternative method, the method 2-2 (14-52) may be applied.

FIG. 14 is a diagram illustrating a second embodiment of an efficientfrequency measurement method in an RRC idle mode or an RRC inactive modeaccording to an embodiment of the disclosure.

In FIG. 14, the base station or cell may set configuration informationfor the RRC idle mode or RRC inactive mode frequency measurement to theUE by using first frequency measurement configuration information 14-10in the RRCRelease message or second frequency measurement configurationinformation 14-20 in the system information.

If the received RRCRelease message contains the first frequencyconfiguration information, the UE may drive a timer by applying firsttimer value information of the first frequency configuration informationand start the RRC idle mode or RRC inactive mode frequency measurement(i.e., early measurement). In addition, if the first frequencyconfiguration information contains first area configuration information,the UE may identify an identifier of a cell on which the UE campsthrough the cell selection or reselection procedure, and may determinewhether to perform the early frequency measurement of the RRC idle modeor RRC inactive mode. If the first frequency configuration informationdoes not contain first frequency list information to be measured, and ifthe second frequency configuration is broadcasted in the systeminformation of the camping cell, the UE may perform the RRC idle mode orRRC inactive mode frequency measurement, based on the second frequencyconfiguration information (e.g., second frequency list information),store a valid measurement result, and report the stored measurementresult to the network as described in FIG. 6 or 7 when establishing anRRC connection later.

In the second embodiment of the efficient RRC idle mode or RRC inactivemode frequency measurement method as shown in FIG. 14, the UE mayreceive the first frequency configuration information through theRRCRelease message, transition to the RRC idle mode or RRC inactivemode, and perform the frequency measurement. In addition, the UE mayreceive the second frequency configuration information through thesystem information of a cell on which the UE camps through the cellselection or reselection procedure.

In the second embodiment, that the UE may receive the first frequencyconfiguration information and/or the second frequency configurationinformation, prioritize the second frequency configuration informationwhen performing the RRC idle mode or RRC inactive mode frequencymeasurement, and perform the frequency measurement based on the secondfrequency configuration information only. In addition, the UE mayperform the frequency measurement in consideration of the firstfrequency configuration information with respect to configurationinformation that is not contained in the second frequency configurationinformation.

For example, the UE may receive the first frequency configurationinformation 14-10 in the RRCRelease message from the first cell,transition to the RRC idle mode or RRC inactive mode, and then receivethe second frequency configuration information 14-20 in the systeminformation from the first cell or a new second cell through the cellselection or reselection procedure.

A first frequency list of the first frequency configuration information14-10 may contain, as target frequencies to be measured, frequency 1(14-01), frequency 2 (14-02), frequency 3 (14-03), frequency 4 (14-04),frequency 5 (14-05), and frequency 6 (14-06). Among these frequencies,only frequency 1 (14-01), frequency 2 (14-02), frequency 3 (14-03), andfrequency 5 (14-05) may be configured with threshold value informationused as a criterion for measurement and report for each frequency, firstconfiguration information for SSB measurement for each frequency, or afirst reporting method for measurement report for each frequency.

A second frequency list of the second frequency configurationinformation 14-20 may contain, as target frequencies to be measured,frequency 3 (14-03), frequency 4 (14-04), frequency 5 (14-05), frequency6 (14-06), frequency 7 (14-07), and frequency 8 (14-08). Among thesefrequencies, only frequency 3 (14-03), frequency 4 (14-04), frequency 7(14-07), and frequency 8 (14-08) may be configured with threshold valueinformation used as a criterion for measurement and report for eachfrequency, second configuration information for SSB measurement for eachfrequency, or a second reporting method for measurement report for eachfrequency.

Upon receiving the first frequency configuration information 14-10 orthe second frequency configuration information 14-20, the UE may selectfrequencies to be measured, and then apply one of the following methodsso as to determine frequency configurations to be applied to therespective frequencies.

-   -   Method 2-1 (14-51): The UE prioritizes the second frequency        configuration information 14-20 to perform frequency        measurement. Therefore, the UE may perform the frequency        measurement only for frequencies 14-51 (i.e., frequency 3        (14-03), frequency 4 (14-04), frequency 5 (14-05), frequency 6        (14-06), frequency 7 (14-07), and frequency 8 (14-08)) set in        the second frequency list by applying frequency measurement        configuration information for each frequency (e.g., the        threshold value information used as a criterion for measurement        and report for each frequency, the second configuration        information for SSB measurement for each frequency, or the        second reporting method for measurement report for each        frequency) set in the second frequency configuration information        14-20, determine a valid frequency measurement result, construct        a result to be reported, and store the constructed result.        Specifically, in the method 2-1, the UE may perform the        frequency measurement by applying second configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency, based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is no second        configuration information for SSB measurement for a target        frequency to be measured, the UE may not perform the measurement        for the frequency to reduce battery consumption. In one        alternative method, even when there is no second configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency, the UE may perform the        RRC idle mode or RRC inactive mode frequency measurement by        being implemented to synchronize for the frequency, search for        SSB signals from the beginning, and derive parameter values of        periodicity, offset, and duration.    -   Method 2-2 (14-52): The UE prioritizes the second frequency        configuration information 14-20 to perform frequency        measurement. Therefore, the UE may perform the frequency        measurement only for frequencies 14-52 (i.e., frequency 3        (14-03), frequency 4 (14-04), frequency 5 (14-05), frequency 6        (14-06), frequency 7 (14-07), and frequency 8 (14-08)) set in        the second frequency list by applying frequency measurement        configuration information for each frequency (e.g., the        threshold value information used as a criterion for measurement        and report for each frequency, the second configuration        information for SSB measurement for each frequency, or the        second reporting method for measurement report for each        frequency) set in the second frequency configuration information        14-20, determine a valid frequency measurement result, construct        a result to be reported, and store the constructed result.        Specifically, in the method 2-2, the UE may perform the        frequency measurement by applying second configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency, based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is no second        configuration information for SSB measurement for a target        frequency (e.g., frequency 5 (14-05)) to be measured, but if the        first frequency configuration information received in the        RRCRelease message contains first configuration information for        SSB measurement for the frequency, the UE may perform the        frequency measurement by applying the first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency (e.g., frequency 5        (14-05)), based on a reference timing of a serving cell on which        the UE camps through the cell selection or reselection        procedure. If there is neither first configuration information        nor second configuration information for SSB measurement for a        target frequency to be measured, the UE may not perform the        measurement for the frequency to reduce battery consumption. In        one alternative method, even if there is no first configuration        information for SSB measurement for each frequency, or even if        there is no second configuration information for SSB measurement        for each frequency, the UE may perform the RRC idle mode or RRC        inactive mode frequency measurement by being implemented to        synchronize for the frequency, search for SSB signals from the        beginning, and derive parameter values of periodicity, offset,        and duration.

FIG. 15 is a diagram illustrating a third embodiment of an efficientfrequency measurement method in an RRC idle mode or an RRC inactive modeaccording to an embodiment of the disclosure.

In FIG. 15, the base station or cell may set configuration informationfor the RRC idle mode or RRC inactive mode frequency measurement to theUE by using first frequency measurement configuration information 15-10in the RRCRelease message or second frequency measurement configurationinformation 15-20 in the system information.

If the received RRCRelease message contains the first frequencyconfiguration information, the UE may drive a timer by applying firsttimer value information of the first frequency configuration informationand start the RRC idle mode or RRC inactive mode frequency measurement(i.e., early measurement). In addition, if the first frequencyconfiguration information contains first area configuration information,the UE may identify an identifier of a cell on which the UE campsthrough the cell selection or reselection procedure, and may determinewhether to perform the early frequency measurement of the RRC idle modeor RRC inactive mode. If the first frequency configuration informationdoes not contain first frequency list information to be measured, and ifthe second frequency configuration is broadcasted in the systeminformation of the camping cell, the UE may perform the RRC idle mode orRRC inactive mode frequency measurement, based on the second frequencyconfiguration information (e.g., second frequency list information),store a valid measurement result, and report the stored measurementresult to the network as described in FIG. 6 or 7 when establishing anRRC connection later.

In the third embodiment of the efficient RRC idle mode or RRC inactivemode frequency measurement method as shown in FIG. 15, the UE mayreceive the first frequency configuration information through theRRCRelease message, transition to the RRC idle mode or RRC inactivemode, and perform the frequency measurement. In addition, the UE mayreceive the second frequency configuration information through thesystem information of a cell on which the UE camps through the cellselection or reselection procedure.

The third embodiment is characterized in that the UE receives the firstfrequency configuration information and/or the second frequencyconfiguration information, compares the first frequency configurationinformation and the second frequency configuration information whenperforming the RRC idle mode or RRC inactive mode frequency measurement,and performs the frequency measurement for frequencies corresponding toan intersection of the first frequency list and the second frequencylist, based on the first frequency configuration information or thesecond frequency configuration information. In addition, the UE mayperform the frequency measurement in consideration of the secondfrequency configuration information with respect to configurationinformation that is not contained in the first frequency configurationinformation, and may perform the frequency measurement in considerationof the first frequency configuration information with respect toconfiguration information that is not contained in the second frequencyconfiguration information.

For example, the UE may receive the first frequency configurationinformation 15-10 in the RRCRelease message from the first cell,transition to the RRC idle mode or RRC inactive mode, and then receivethe second frequency configuration information 15-20 in the systeminformation from the first cell or a new second cell through the cellselection or reselection procedure.

A first frequency list of the first frequency configuration information15-10 may contain, as target frequencies to be measured, frequency 1(15-01), frequency 2 (15-02), frequency 3 (15-03), frequency 4 (15-04),frequency 5 (15-05), and frequency 6 (15-06). Among these frequencies,only frequency 1 (15-01), frequency 2 (15-02), frequency 3 (15-03), andfrequency 5 (15-05) may be configured with threshold value informationused as a criterion for measurement and report for each frequency, firstconfiguration information for SSB measurement for each frequency, or afirst reporting method for measurement report for each frequency.

A second frequency list of the second frequency configurationinformation 15-20 may contain, as target frequencies to be measured,frequency 3 (15-03), frequency 4 (15-04), frequency 5 (15-05), frequency6 (15-06), frequency 7 (15-07), and frequency 8 (15-08). Among thesefrequencies, only frequency 3 (15-03), frequency 4 (15-04), frequency 7(15-07), and frequency 8 (15-08) may be configured with threshold valueinformation used as a criterion for measurement and report for eachfrequency, second configuration information for SSB measurement for eachfrequency, or a second reporting method for measurement report for eachfrequency.

Upon receiving the first frequency configuration information 15-10 orthe second frequency configuration information 15-20, the UE may selectfrequencies to be measured, and then apply one of the following methodsso as to determine frequency configurations to be applied to therespective frequencies.

-   -   Method 3-1 (15-51): Upon receiving the first frequency        configuration information 15-10 or the second frequency        configuration information 15-20, the UE compares the first        frequency list information of the first frequency configuration        information and the second frequency list information of the        second frequency configuration information, selects frequencies        corresponding to an intersection, and performs frequency        measurement for the selected frequencies. Therefore, the UE may        perform the frequency measurement only for frequencies 15-30        corresponding to the intersection between the first and second        frequency lists (i.e., frequency 3 (15-03), frequency 4 (15-04),        frequency 5 (15-05), and frequency 6 (15-06)) by applying        frequency measurement configuration information for each        frequency (e.g., the threshold value information used as a        criterion for measurement and report for each frequency, the        first configuration information for SSB measurement for each        frequency, or the first reporting method for measurement report        for each frequency) set in the first frequency configuration        information, determine a valid frequency measurement result,        construct a result to be reported, and store the constructed        result. Specifically, in the method 3-1, the UE may perform the        frequency measurement by applying first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency, based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is no first        configuration information for SSB measurement for a target        frequency to be measured, the UE may not perform the measurement        for the frequency to reduce battery consumption. In one        alternative method, even when there is no first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency, the UE may perform the        RRC idle mode or RRC inactive mode frequency measurement by        being implemented to synchronize for the frequency, search for        SSB signals from the beginning, and derive parameter values of        periodicity, offset, and duration. In another alternative        method, the UE may store a reference timing of a cell from which        the RRCRelease message is received, and perform the measurement        by applying the first configuration information for SSB        measurement for each frequency, based on the stored timing. In        such method 3-1, the UE performs the frequency measurement based        on the first frequency configuration information only, so that        it is not necessary to read a lot of system information, thereby        reducing the battery consumption of the UE.    -   Method 3-2 (15-52): Upon receiving the first frequency        configuration information 15-10 or the second frequency        configuration information 15-20, the UE compares the first        frequency list information of the first frequency configuration        information and the second frequency list information of the        second frequency configuration information, selects frequencies        corresponding to an intersection, and performs frequency        measurement for the selected frequencies. Therefore, the UE may        perform the frequency measurement only for frequencies 15-30        corresponding to the intersection between the first and second        frequency lists (i.e., frequency 3 (15-03), frequency 4 (15-04),        frequency 5 (15-05), and frequency 6 (15-06)) by applying        frequency measurement configuration information for each        frequency (e.g., the threshold value information used as a        criterion for measurement and report for each frequency, the        first configuration information for SSB measurement for each        frequency, or the first reporting method for measurement report        for each frequency) set in the first frequency configuration        information, determine a valid frequency measurement result,        construct a result to be reported, and store the constructed        result. Specifically, in the method 3-2, the UE may perform the        frequency measurement by applying first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency, based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is no first        configuration information for SSB measurement for a target        frequency (e.g., frequency 4 (15-04)) to be measured, but if the        second frequency configuration information received in the        system information contains second configuration information for        SSB measurement for the frequency, the UE may perform the        frequency measurement by applying the second configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency (e.g., frequency 4        (15-04)), based on a reference timing of a serving cell on which        the UE camps through the cell selection or reselection        procedure. If there is neither first configuration information        nor second configuration information for SSB measurement for a        target frequency to be measured, the UE may not perform the        measurement for the frequency to reduce battery consumption. In        one alternative method, even if there is no first configuration        information for SSB measurement for each frequency, or even if        there is no second configuration information for SSB measurement        for each frequency, the UE may perform the RRC idle mode or RRC        inactive mode frequency measurement by being implemented to        synchronize for the frequency, search for SSB signals from the        beginning, and derive parameter values of periodicity, offset,        and duration.    -   Method 3-3 (15-53): Upon receiving the first frequency        configuration information 15-10 or the second frequency        configuration information 15-20, the UE compares the first        frequency list information of the first frequency configuration        information and the second frequency list information of the        second frequency configuration information, selects frequencies        corresponding to an intersection, and performs frequency        measurement for the selected frequencies. Therefore, the UE may        perform the frequency measurement only for frequencies 15-30        corresponding to the intersection between the first and second        frequency lists (i.e., frequency 3 (15-03), frequency 4 (15-04),        frequency 5 (15-05), and frequency 6 (15-06)) by applying        frequency measurement configuration information for each        frequency (e.g., the threshold value information used as a        criterion for measurement and report for each frequency, the        second configuration information for SSB measurement for each        frequency, or the second reporting method for measurement report        for each frequency) set in the second frequency configuration        information, determine a valid frequency measurement result,        construct a result to be reported, and store the constructed        result. Specifically, in the method 3-3, the UE may perform the        frequency measurement by applying second configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency, based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is no second        configuration information for SSB measurement for a target        frequency to be measured, the UE may not perform the measurement        for the frequency to reduce battery consumption. In one        alternative method, even when there is no second configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency, the UE may perform the        RRC idle mode or RRC inactive mode frequency measurement by        being implemented to synchronize for the frequency, search for        SSB signals from the beginning, and derive parameter values of        periodicity, offset, and duration.    -   Method 3-4 (15-54): Upon receiving the first frequency        configuration information 15-10 or the second frequency        configuration information 15-20, the UE compares the first        frequency list information of the first frequency configuration        information and the second frequency list information of the        second frequency configuration information, selects frequencies        corresponding to an intersection, and performs frequency        measurement for the selected frequencies. Therefore, the UE may        perform the frequency measurement only for frequencies 15-30        corresponding to the intersection between the first and second        frequency lists (i.e., frequency 3 (15-03), frequency 4 (15-04),        frequency 5 (15-05), and frequency 6 (15-06)) by applying        frequency measurement configuration information for each        frequency (e.g., the threshold value information used as a        criterion for measurement and report for each frequency, the        second configuration information for SSB measurement for each        frequency, or the second reporting method for measurement report        for each frequency) set in the second frequency configuration        information, determine a valid frequency measurement result,        construct a result to be reported, and store the constructed        result. Specifically, in the method 3-4, the UE may perform the        frequency measurement by applying second configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency, based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is no second        configuration information for SSB measurement for a target        frequency (e.g., frequency 5 (15-05)) to be measured, but if the        first frequency configuration information received in the        RRCRelease message contains first configuration information for        SSB measurement for the frequency, the UE may perform the        frequency measurement by applying the first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency (e.g., frequency 5        (15-05)), based on a reference timing of a serving cell on which        the UE camps through the cell selection or reselection        procedure. If there is neither first configuration information        nor second configuration information for SSB measurement for a        target frequency to be measured, the UE may not perform the        measurement for the frequency to reduce battery consumption. In        one alternative method, even if there is no first configuration        information for SSB measurement for each frequency, or even if        there is no second configuration information for SSB measurement        for each frequency, the UE may perform the RRC idle mode or RRC        inactive mode frequency measurement by being implemented to        synchronize for the frequency, search for SSB signals from the        beginning, and derive parameter values of periodicity, offset,        and duration.

FIG. 16 is a diagram illustrating a fourth embodiment of an efficientfrequency measurement method in an RRC idle mode or an RRC inactive modeaccording to an embodiment of the disclosure.

In FIG. 16, the base station or cell may set configuration informationfor the RRC idle mode or RRC inactive mode frequency measurement to theUE by using first frequency measurement configuration information 16-10in the RRCRelease message or second frequency measurement configurationinformation 16-20 in the system information.

If the received RRCRelease message contains the first frequencyconfiguration information, the UE may drive a timer by applying firsttimer value information of the first frequency configuration informationand start the RRC idle mode or RRC inactive mode frequency measurement(i.e., early measurement). In addition, if the first frequencyconfiguration information contains first area configuration information,the UE may identify an identifier of a cell on which the UE campsthrough the cell selection or reselection procedure, and may determinewhether to perform the early frequency measurement of the RRC idle modeor RRC inactive mode. If the first frequency configuration informationdoes not contain first frequency list information to be measured, and ifthe second frequency configuration is broadcasted in the systeminformation of the camping cell, the UE may perform the RRC idle mode orRRC inactive mode frequency measurement, based on the second frequencyconfiguration information (e.g., second frequency list information),store a valid measurement result, and report the stored measurementresult to the network as described in FIG. 6 or 7 when establishing anRRC connection later.

In the fourth embodiment of the efficient RRC idle mode or RRC inactivemode frequency measurement method as shown in FIG. 16, the UE mayreceive the first frequency configuration information through theRRCRelease message, transition to the RRC idle mode or RRC inactivemode, and perform the frequency measurement. In addition, the UE mayreceive the second frequency configuration information through thesystem information of a cell on which the UE camps through the cellselection or reselection procedure.

The fourth embodiment is characterized in that the UE receives the firstfrequency configuration information and/or the second frequencyconfiguration information, compares the first frequency configurationinformation and the second frequency configuration information whenperforming the RRC idle mode or RRC inactive mode frequency measurement,and performs the frequency measurement for frequencies corresponding toa union of the first frequency list and the second frequency list, basedon the first frequency configuration information or the second frequencyconfiguration information. In addition, the UE may perform the frequencymeasurement in consideration of the second frequency configurationinformation with respect to configuration information that is notcontained in the first frequency configuration information, and mayperform the frequency measurement in consideration of the firstfrequency configuration information with respect to configurationinformation that is not contained in the second frequency configurationinformation.

For example, the UE may receive the first frequency configurationinformation 16-10 in the RRCRelease message from the first cell,transition to the RRC idle mode or RRC inactive mode, and then receivethe second frequency configuration information 16-20 in the systeminformation from the first cell or a new second cell through the cellselection or reselection procedure.

A first frequency list of the first frequency configuration information16-10 may contain, as target frequencies to be measured, frequency 1(16-01), frequency 2 (16-02), frequency 3 (16-03), frequency 4 (16-04),frequency 5 (16-05), and frequency 6 (16-06). Among these frequencies,only frequency 1 (16-01), frequency 2 (16-02), frequency 3 (16-03), andfrequency 5 (16-05) may be configured with threshold value informationused as a criterion for measurement and report for each frequency, firstconfiguration information for SSB measurement for each frequency, or afirst reporting method for measurement report for each frequency.

A second frequency list of the second frequency configurationinformation 16-20 may contain, as target frequencies to be measured,frequency 3 (16-03), frequency 4 (16-04), frequency 5 (16-05), frequency6 (16-06), frequency 7 (16-07), and frequency 8 (16-08). Among thesefrequencies, only frequency 3 (16-03), frequency 4 (16-04), frequency 7(16-07), and frequency 8 (16-08) may be configured with threshold valueinformation used as a criterion for measurement and report for eachfrequency, second configuration information for SSB measurement for eachfrequency, or a second reporting method for measurement report for eachfrequency.

Upon receiving the first frequency configuration information 16-10 orthe second frequency configuration information 16-20, the UE may selectfrequencies to be measured, and then apply one of the following methodsso as to determine frequency configurations to be applied to therespective frequencies.

-   -   Method 4-1 (16-51): Upon receiving the first frequency        configuration information 16-10 or the second frequency        configuration information 16-20, the UE compares the first        frequency list information of the first frequency configuration        information and the second frequency list information of the        second frequency configuration information, selects frequencies        corresponding to a union, and performs frequency measurement for        the selected frequencies. Therefore, the UE may perform the        frequency measurement only for frequencies 16-10, 16-20, and        16-30 corresponding to the union between the first and second        frequency lists (i.e., frequency 1 (16-01), frequency 2 (16-02),        frequency 3 (16-03), frequency 4 (16-04), frequency 5 (16-05),        frequency 6 (16-06), frequency 7 (16-07), and frequency 8        (16-08)) by applying frequency measurement configuration        information for each frequency (e.g., the threshold value        information used as a criterion for measurement and report for        each frequency, the first or second configuration information        for SSB measurement for each frequency, or the first or second        reporting method for measurement report for each frequency) set        in the first or second frequency configuration information,        determine a valid frequency measurement result, construct a        result to be reported, and store the constructed result.        Specifically, in the method 4-1, the UE may perform the        frequency measurement by applying first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency of the first frequency        list or applying second configuration information for SSB        measurement for each frequency of the second frequency list,        based on a reference timing of a serving cell on which the UE        camps through the cell selection or reselection procedure. In        the method 4-1, the UE may prioritize the first frequency        configuration information for frequencies corresponding to an        intersection between the first and second frequency lists. If        there are both the first frequency configuration information and        the second frequency configuration information with respect to a        target frequency (e.g., frequency 3 (16-03)) to be measured, the        UE may prioritize the first frequency configuration information.        If there is no first configuration information for SSB        measurement for a target frequency to be measured in the first        frequency list, or if there is no second configuration        information for SSB measurement for a target frequency to be        measured in the second frequency list, the UE may not perform        the measurement for the frequency to reduce battery consumption.        In one alternative method, even when there is no first        configuration information for SSB measurement for the target        frequency in the first frequency list, or even when there is no        second configuration information for SSB measurement for the        target frequency in the second frequency list, the UE may        perform the RRC idle mode or RRC inactive mode frequency        measurement by being implemented to synchronize for the        frequency, search for SSB signals from the beginning, and derive        parameter values of periodicity, offset, and duration.    -   Method 4-2 (16-52): Upon receiving the first frequency        configuration information 16-10 or the second frequency        configuration information 16-20, the UE compares the first        frequency list information of the first frequency configuration        information and the second frequency list information of the        second frequency configuration information, selects frequencies        corresponding to a union, and performs frequency measurement for        the selected frequencies. Therefore, the UE may perform the        frequency measurement only for frequencies 16-10, 16-20, and        16-30 corresponding to the union between the first and second        frequency lists (i.e., frequency 1 (16-01), frequency 2 (16-02),        frequency 3 (16-03), frequency 4 (16-04), frequency 5 (16-05),        frequency 6 (16-06), frequency 7 (16-07), and frequency 8        (16-08)) by applying frequency measurement configuration        information for each frequency (e.g., the threshold value        information used as a criterion for measurement and report for        each frequency, the first or second configuration information        for SSB measurement for each frequency, or the first or second        reporting method for measurement report for each frequency) set        in the first or second frequency configuration information,        determine a valid frequency measurement result, construct a        result to be reported, and store the constructed result.        Specifically, in the method 4-2, the UE may perform the        frequency measurement by applying first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency of the first frequency        list or applying second configuration information for SSB        measurement for each frequency of the second frequency list,        based on a reference timing of a serving cell on which the UE        camps through the cell selection or reselection procedure. In        the method 4-2, the UE may prioritize the first frequency        configuration information for frequencies corresponding to an        intersection between the first and second frequency lists. If        there are both the first frequency configuration information and        the second frequency configuration information with respect to a        target frequency (e.g., frequency 3 (16-03)) to be measured, the        UE may prioritize the first frequency configuration information.        If there is no first configuration information for SSB        measurement for a target frequency (e.g., frequency 4 (16-04))        to be measured, but if the second frequency configuration        information received in the system information contains second        configuration information for SSB measurement for the frequency,        the UE may perform the frequency measurement by applying the        second configuration information (e.g., periodicity, offset,        and/or duration of smtc) for SSB measurement for the frequency        (e.g., frequency 4 (16-04)), based on a reference timing of a        serving cell on which the UE camps through the cell selection or        reselection procedure. In addition, if there is no second        configuration information for SSB measurement for a target        frequency (e.g., frequency 5 (16-05)) to be measured, but if the        first frequency configuration information received in the        RRCRelease message contains first configuration information for        SSB measurement for the frequency, the UE may perform the        frequency measurement by applying the first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for the frequency (e.g., frequency 5        (16-05)), based on a reference timing of a serving cell on which        the UE camps through the cell selection or reselection        procedure. If there is neither first configuration information        nor second configuration information for SSB measurement for a        target frequency to be measured, the UE may not perform the        measurement for the frequency to reduce battery consumption. In        one alternative method, even if there is no first configuration        information for SSB measurement for each frequency, or even if        there is no second configuration information for SSB measurement        for each frequency, the UE may perform the RRC idle mode or RRC        inactive mode frequency measurement by being implemented to        synchronize for the frequency, search for SSB signals from the        beginning, and derive parameter values of periodicity, offset,        and duration.    -   Method 4-3 (16-53): Upon receiving the first frequency        configuration information 16-10 or the second frequency        configuration information 16-20, the UE compares the first        frequency list information of the first frequency configuration        information and the second frequency list information of the        second frequency configuration information, selects frequencies        corresponding to a union, and performs frequency measurement for        the selected frequencies. Therefore, the UE may perform the        frequency measurement only for frequencies 16-10, 16-20, and        16-30 corresponding to the union between the first and second        frequency lists (i.e., frequency 1 (16-01), frequency 2 (16-02),        frequency 3 (16-03), frequency 4 (16-04), frequency 5 (16-05),        frequency 6 (16-06), frequency 7 (16-07), and frequency 8        (16-08)) by applying frequency measurement configuration        information for each frequency (e.g., the threshold value        information used as a criterion for measurement and report for        each frequency, the first or second configuration information        for SSB measurement for each frequency, or the first or second        reporting method for measurement report for each frequency) set        in the first or second frequency configuration information,        determine a valid frequency measurement result, construct a        result to be reported, and store the constructed result.        Specifically, in the method 4-3, the UE may perform the        frequency measurement by applying first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency of the first frequency        list or applying second configuration information for SSB        measurement for each frequency of the second frequency list,        based on a reference timing of a serving cell on which the UE        camps through the cell selection or reselection procedure. In        the method 4-3, the UE may prioritize the second frequency        configuration information for frequencies corresponding to an        intersection between the first and second frequency lists. If        there are both the first frequency configuration information and        the second frequency configuration information with respect to a        target frequency (e.g., frequency 3 (16-03)) to be measured, the        UE may prioritize the second frequency configuration        information. If there is no first configuration information for        SSB measurement for a target frequency to be measured in the        first frequency list, or if there is no second configuration        information for SSB measurement for a target frequency to be        measured in the second frequency list, the UE may not perform        the measurement for the frequency to reduce battery consumption.        In one alternative method, even when there is no first        configuration information for SSB measurement for the target        frequency in the first frequency list, or even when there is no        second configuration information for SSB measurement for the        target frequency in the second frequency list, the UE may        perform the RRC idle mode or RRC inactive mode frequency        measurement by being implemented to synchronize for the        frequency, search for SSB signals from the beginning, and derive        parameter values of periodicity, offset, and duration.    -   Method 4-4 (16-54): Upon receiving the first frequency        configuration information 16-10 or the second frequency        configuration information 16-20, the UE compares the first        frequency list information of the first frequency configuration        information and the second frequency list information of the        second frequency configuration information, selects frequencies        corresponding to a union, and performs frequency measurement for        the selected frequencies. Therefore, the UE may perform the        frequency measurement only for frequencies 16-10, 16-20, and        16-30 corresponding to the union between the first and second        frequency lists (i.e., frequency 1 (16-01), frequency 2 (16-02),        frequency 3 (16-03), frequency 4 (16-04), frequency 5 (16-05),        frequency 6 (16-06), frequency 7 (16-07), and frequency 8        (16-08)) by applying frequency measurement configuration        information for each frequency (e.g., the threshold value        information used as a criterion for measurement and report for        each frequency, the first or second configuration information        for SSB measurement for each frequency, or the first or second        reporting method for measurement report for each frequency) set        in the first or second frequency configuration information,        determine a valid frequency measurement result, construct a        result to be reported, and store the constructed result.        Specifically, in the method 4-4, the UE may perform the        frequency measurement by applying first configuration        information (e.g., periodicity, offset, and/or duration of smtc)        for SSB measurement for each frequency of the first frequency        list or applying second configuration information for SSB        measurement for each frequency of the second frequency list,        based on a reference timing of a serving cell on which the UE        camps through the cell selection or reselection procedure. In        the method 4-4, the UE may prioritize the second frequency        configuration information for frequencies corresponding to an        intersection between the first and second frequency lists. If        there are both the first frequency configuration information and        the second frequency configuration information with respect to a        target frequency (e.g., frequency 3 (16-03)) to be measured, the        UE may prioritize the second frequency configuration        information. If there is no first configuration information for        SSB measurement for a target frequency (e.g., frequency 4        (16-04)) to be measured, but if the second frequency        configuration information received in the system information        contains second configuration information for SSB measurement        for the frequency, the UE may perform the frequency measurement        by applying the second configuration information (e.g.,        periodicity, offset, and/or duration of smtc) for SSB        measurement for the frequency (e.g., frequency 4 (16-04)), based        on a reference timing of a serving cell on which the UE camps        through the cell selection or reselection procedure. In        addition, if there is no second configuration information for        SSB measurement for a target frequency (e.g., frequency 5        (16-05)) to be measured, but if the first frequency        configuration information received in the RRCRelease message        contains first configuration information for SSB measurement for        the frequency, the UE may perform the frequency measurement by        applying the first configuration information (e.g., periodicity,        offset, and/or duration of smtc) for SSB measurement for the        frequency (e.g., frequency 5 (16-05)), based on a reference        timing of a serving cell on which the UE camps through the cell        selection or reselection procedure. If there is neither first        configuration information nor second configuration information        for SSB measurement for a target frequency to be measured, the        UE may not perform the measurement for the frequency to reduce        battery consumption. In one alternative method, even if there is        no first configuration information for SSB measurement for each        frequency, or even if there is no second configuration        information for SSB measurement for each frequency, the UE may        perform the RRC idle mode or RRC inactive mode frequency        measurement by being implemented to synchronize for the        frequency, search for SSB signals from the beginning, and derive        parameter values of periodicity, offset, and duration.

Meanwhile, each of the above-described first, second, third, and fourthembodiments may also be applied to other cases where the base station ornetwork sets the configuration information for the RRC idle mode or RRCinactive mode frequency measurement by using only the first frequencyconfiguration information of the RRCRelease message. Similarly, each ofthe above-described first, second, third, and fourth embodiments mayalso be applied to other cases where the base station or network setsthe configuration information for the RRC idle mode or RRC inactive modefrequency measurement by using only the second frequency configurationinformation of the system information.

FIG. 17 is a diagram illustrating a method for a terminal to perform afrequency measurement in an RRC idle mode or an RRC inactive mode in anetwork that is not synchronized between different frequencies or cellsaccording to an embodiment of the disclosure.

In FIG. 17, the UE that transmits/receives data in the RRC connectedmode in a current cell 17-01 (first cell) may receive the RRCReleasemessage from the base station of the current cell 17-01, transition tothe RRC idle mode or RRC inactive mode, and move while performing thecell selection or reselection procedure. The RRCRelease message maycontain the first frequency configuration information. In addition, theRRC idle mode or RRC inactive mode UE may camp on a suitable cellthrough the cell selection or reselection procedure and acquire systeminformation. The UE may receive the second frequency configurationinformation in the system information.

If the received RRCRelease message contains the first frequencyconfiguration information, the UE may drive a timer by applying firsttimer value information of the first frequency configuration informationand start early frequency measurement of the RRC idle mode or RRCinactive mode. In addition, if the first frequency configurationinformation contains first area configuration information, the UE mayidentify an identifier of the camping cell and determine whether toperform the early frequency measurement of the RRC idle mode or RRCinactive mode.

If the UE is in a service area of the first cell 17-01, the UE mayperform the early frequency measurement of the RRC idle mode or RRCinactive mode, based on the first frequency configuration informationreceived in the RRCRelease message or the second frequency configurationinformation broadcasted as the system information by the first cell17-01. Specifically, the UE may perform the early frequency measurementof the RRC idle mode or RRC inactive mode according to theabove-described first, second, third, or fourth embodiment.

If the UE moves from the first cell 17-01 to a service area of a secondcell 17-02 and camps on the second cell 17-02, the UE may perform theRRC idle mode or RRC inactive mode frequency measurement based on thefirst frequency configuration information received in the RRCReleasemessage or the second frequency configuration information broadcasted asthe system information by the second cell 17-02. Specifically, the UEmay perform the early frequency measurement of the RRC idle mode or RRCinactive mode according to the above-described first, second, third, orfourth embodiment.

Described hereinafter is a method for the UE to determine a referencetiming when performing the frequency measurement based on the firstfrequency configuration information that has been set by the basestation or network through an RRC message (e.g., the RRCRelease messageor the RRCReconfiguration message). The reference timing determinationmethod to be described below may be applied to each of theabove-described first, second, third, and fourth embodiments.

-   -   Reference timing determination method 1: In the reference timing        determination method 1, the network may assume that all        frequencies of the network are managed to be synchronized, or        assume that synchronized information is broadcasted through the        system information of each cell. Therefore, the base station may        set the first frequency configuration information in the RRC        message to the UE, and the UE may determine a reference timing        for the frequency measurement of the RRC idle mode or RRC        inactive mode, based on a reference timing (e.g., SFN 0) of a        cell on or with which the UE camps or synchronizes through the        cell selection or reselection procedure, and may apply SSB        configuration information for each frequency to perform the RRC        idle mode or RRC inactive mode frequency measurement.    -   Reference timing determination method 2: In the reference timing        determination method 2, the network does not assume that all        frequencies of the network are managed to be synchronized.        Therefore, the base station may assume a current cell as a        reference timing and thereby set the first frequency        configuration information in the RRC message to the UE. Then,        the UE may store the cell reference timing (e.g., SFN 0) of the        first frequency configuration information received through the        RRC message, determine a reference timing for the frequency        measurement of the RRC idle mode or RRC inactive mode, based on        the stored reference timing, and apply SSB configuration        information for each frequency to perform the RRC idle mode or        RRC inactive mode frequency measurement.    -   Reference timing determination method 3: In the reference timing        determination method 3, the network does not assume that all        frequencies of the network are managed to be synchronized.        Therefore, the base station may assume a current cell or a cell        indicated in the first area configuration information as a        reference timing and thereby set the first frequency        configuration information in the RRC message to the UE. Then,        the UE may perform the RRC idle mode or RRC inactive mode        frequency measurement only when a cell on which the UE camps        through the cell selection or reselection procedure is a cell        sending the first frequency configuration information through        the RRC message or a cell indicated in the first area        information of the first frequency configuration information. In        other cases, the UE may stop the frequency measurement.        Therefore, the UE may store the cell reference timing (e.g.,        SFN 0) of the first frequency configuration information received        through the RRC message and, based on the stored reference        timing, determine a reference timing for the frequency        measurement, or alternatively determine a reference timing for        the frequency measurement, based on a reference timing of the        camping cell. Then, based on the reference timing, the UE may        apply SSB configuration information for each frequency to        perform the RRC idle mode or RRC inactive frequency measurement.    -   Reference timing determination method 4: In the reference timing        determination method 4, the network does not assume that all        frequencies of the network are managed to be synchronized.        Therefore, the base station may set only frequencies        synchronized in the entire network (assuming that frequencies        included in the first frequency list are synchronized in the        entire network) to the UE in the first frequency configuration        information through the RRC message. Thus, the UE may        synchronize, for each frequency of the first frequency list set        in the first frequency configuration information, with any cell        of the corresponding frequency, determine a reference timing        based on that of the synchronized cell, and apply SSB        configuration information for each frequency to perform the RRC        idle mode or RRC inactive frequency measurement.    -   Reference timing determination method 5: In the reference timing        determination method 5, the network does not assume that all        frequencies of the network are managed to be synchronized.        Therefore, the base station may set only frequencies        synchronized in the entire network (assuming that frequencies        included in the first frequency list are synchronized in the        entire network) to the UE in the first frequency configuration        information through the RRC message. Thus, the UE may        synchronize, for a certain frequency of the first frequency list        set in the first frequency configuration information, with any        cell of any frequency of the first frequency list, determine a        reference timing based on that of the synchronized cell, and        apply SSB configuration information for each frequency to        perform the RRC idle mode or RRC inactive frequency measurement.    -   Reference timing determination method 6: In the reference timing        determination method 6, the network does not assume that all        frequencies of the network are managed to be synchronized.        Therefore, the base station may set reference frequencies,        cells, or areas synchronized in the entire network (assuming        that frequencies included in a separate reference list are        synchronized in the entire network) to the UE as a separate        reference list in the first frequency configuration information        through the RRC message. Thus, the UE may synchronize, for a        certain frequency of the first frequency list set in the first        frequency configuration information, with any cell of any        frequency of the separate reference frequency list, determine a        reference timing based on that of the synchronized cell, and        apply SSB configuration information for each frequency to        perform the RRC idle mode or RRC inactive frequency measurement.

The above-described reference timing determination methods 1, 2, 3, 4,5, and 6 may be applied when performing the cell selection orreselection procedure, measuring a neighboring cell, or performing theRRC idle mode or RRC inactive mode frequency measurement, based on thesecond frequency configuration information broadcasted in the systeminformation.

In addition, described hereinafter is a first UE operation forperforming frequency measurement in different methods depending on whichRRC message is used to set the frequency measurement configurationinformation to the UE.

-   -   When a received RRC message is the RRCRelease message, the RRC        connected mode UE transitions to the RRC idle mode or RRC        inactive mode. Then, if the RRC message contains frequency        measurement configuration information (e.g., the first frequency        measurement configuration information for the RRC idle mode or        RRC inactive mode), the UE applies SSB configuration information        or smtc configuration information to a frequency to be measured,        based on a serving cell on which the UE camps through the cell        selection or reselection procedure, and thereby performs the        frequency measurement.    -   When a received RRC message is the RRC Reconfiguration message,        the RRC connected mode UE performs frequency measurement in the        RRC connected mode. If the RRC message contains frequency        measurement configuration information (e.g., the first frequency        measurement configuration information for the RRC connected        mode), the UE applies SSB configuration information or smtc        configuration information to a frequency to be measured, based        on a currently connected PCell, and thereby performs the        frequency measurement.

In addition, described hereinafter is a second UE operation forperforming frequency measurement in different methods depending on whichRRC message is used to set the frequency measurement configurationinformation to the UE.

-   -   When a received RRC message is the RRCRelease message, the RRC        connected mode UE transitions to the RRC idle mode or RRC        inactive mode. Then, if the RRC message contains frequency        measurement configuration information (e.g., the first frequency        measurement configuration information for the RRC idle mode or        RRC inactive mode), the UE applies the above-described first,        second, third, or fourth embodiment and thereby performs the        frequency measurement.    -   When a received RRC message is the RRC Reconfiguration message,        the RRC connected mode UE performs frequency measurement in the        RRC connected mode. If the RRC message contains frequency        measurement configuration information (e.g., the first frequency        measurement configuration information for the RRC connected        mode), the UE applies SSB configuration information or smtc        configuration information to a frequency to be measured, based        on a currently connected PCell, and thereby performs the        frequency measurement.

The RRC message may contain a plurality of the following informationtypes, or a part thereof, to be applied when the UE performs earlyfrequency measurement in the RRC idle mode, RRC inactive mode, or RRCconnected mode.

-   -   Configuration information of frequencies to be measured in the        RRC idle mode or RRC inactive mode        -   Frequency configuration information        -   LTE frequency measurement information group or list (EUTRA            frequency configuration information/list/group)        -   It may be set to contain early measurement setup regarding            which frequencies or frequency bands (e.g., a frequency            list) is to be measured, which order is to be used for            measurement based on frequency priorities, which filtering            method is to be used for measuring frequency strength (e.g.,            an L1, L2, or L3 filtering method, or which calculation            method and which coefficient are to be used for            measurement), which event or condition is to be applied for            starting the frequency measurement, which criterion (e.g., a            signal strength greater than a threshold value) is to be            used for the measurement and report in comparison with a            current serving cell (or a currently camping frequency),            which event or condition is to be applied for reporting a            result of the frequency measurement, which criterion or            condition needs to be satisfied for reporting the frequency            in comparison with a current serving cell (or a currently            camping frequency), or which period is to be applied for            reporting the frequency measurement result.        -   NR frequency measurement information group or list (NR            frequency configuration information/list/group)        -   It may be set to contain early measurement setup regarding            which frequencies or frequency bands (e.g., a frequency            list) is to be measured, which order is to be used for            measurement based on SSB identifier information of each            frequency, SSB transmission resources (e.g., frequency and            time resources, beam identifiers or beam indicators, smtc            configuration information), or priority of each frequency            (or each SSB), which filtering method is to be used for            measuring frequency strength (e.g., an L1, L2, or L3            filtering method, or which calculation method and which            coefficient are to be used for measurement), which event or            condition is to be applied for starting the frequency            measurement, which criterion (e.g., a signal strength            greater than a threshold value) is to be used for the            measurement and report in comparison with a current serving            cell (or a currently camping frequency), which event or            condition is to be applied for reporting a result of the            frequency measurement, which criterion or condition needs to            be satisfied for reporting the frequency in comparison with            a current serving cell (or a currently camping frequency),            or which period is to be applied for reporting the frequency            measurement result.        -   Duration or timer value (e.g., T331) for performing            frequency measurement in the RRC idle mode or RRC inactive            mode: According to an embodiment, the same timer may be set            for both LTE frequency and NR frequency, or different timers            may be set separately for LTE frequency and NR frequency.            Because LTE frequency characteristics (low frequency band)            and NR frequency characteristics (high frequency band) are            different, the use of different timers allows the frequency            measurement time of the UE to be separately adjusted,            thereby saving the battery of the UE. For example, if the            RRCRelease message instructs frequency measurement in the            RRC idle mode or RRC inactive mode, the frequency            measurement may be performed while the timer is running, and            may be stopped when the timer expires.        -   Effective area information for performing frequency            measurement in the RRC idle mode or RRC inactive mode: In            one method, based on a list of physical cell identifiers            (PCIDs), the UE may perform the frequency measurement when            it is in an area (e.g., cell) indicated by the area            information, and may stop the frequency measurement when it            is out of the indicated area. For example, when the UE is            out of the area, the timer may be stopped, and the frequency            measurement may be stopped. In another method, the base            station may use an indicator to instruct the UE,            transitioning to the RRC inactive mode, to determine whether            to use a RAN indication area as the effective area. For            example, when the base station instructs, through the            indicator, the UE transitioning to the RRC inactive mode to            use the RAN indication area as the effective area, the UE            may perform the frequency measurement within the RAN            indication area while maintaining the RRC inactive mode in            the RAN indication area. In still another method, the base            station may instruct, through an indicator, the UE to use            the effective area as the RAN indication area. In yet            another method, the UE may apply the RAN indication area as            the effective area without an indicator in the RRC inactive            mode, and a separate effective area may be set for the UE in            the RRC active mode. Such proposed methods may reduce            signaling overhead because the RRC message indicates both            the RAN indication area and the effective area as a list of            cell identifiers, and may also reduce the UE implementation            burden because it is not required to separately manage the            effective area in the UE implementation.        -   Measurement report threshold value: In a configured            frequency group, one or a plurality of frequencies having            signal strength higher than the threshold value may be            reported.

A condition for the UE to stop the early frequency measurement in theRRC idle mode or inactive mode may be one or more of the followingconditions:

1. when the system information of the current cell supports earlyfrequency measurement result reporting, and after the UE transmits, orwhen the UE attempts to transmit, to the base station an RRC message(e.g., message 5) that there is a measurement result report,

2. when the system information of the current cell does not indicatethat it supports the early frequency measurement result reporting,

3. when the UE establishes a connection with the network whileperforming the RRC idle mode or RRC inactive mode frequency measurement,stops the timer and the measurement upon receiving the RRCSetup messageor RRCResume message through message 4, and then attempts to transmit tothe base station an RRC message (e.g., message 5) that the systeminformation of the current cell supports the early frequency measurementresult reporting and there is a measurement result report,

4. when the measurement report timer (e.g. T331) expires, and

5. when the UE is out of an area indicated by the RRC idle mode or RRCinactive mode measurement area information set in the RRCReleasemessage.

According to one or more of the above conditions, the UE may stop theRRC idle mode or RRC inactive mode frequency measurement.

The UE performs measurement for measurable frequencies in configurationinformation related to early frequency measurement, that is, frequenciessupported by the UE capability (e.g., frequencies available for CA or DCtechnologies), and at this time the UE may select a certain frequency tobe measured preferentially according to predetermined priorities.

In another method, when area configuration information (i.e.,configuration information about an area where the frequency measurementconfiguration is valid) is set to the UE in the frequency measurementconfiguration information of the RRC idle mode or RRC inactive modethrough the RRCRelease message, the UE may stop or restart the RRC idlemode or RRC inactive mode frequency measurement, based on the systeminformation or cell identifier of the camping cell, while a timerindicating a frequency measurement duration is running (if the timer hasnot expired). Specifically, the RRC idle mode or RRC inactive mode UEthat moves while performing the cell selection or reselection proceduremay continue to perform the frequency measurement and run the timerindicating the duration of the frequency measurement if a physical cellidentity of a serving cell on which the UE camps is contained in thearea configuration information. However, if the physical cell identityof the camping, serving cell is not contained in the area configurationinformation, the UE may stop the frequency measurement, continuously runthe timer, and maintain the frequency measurement configurationinformation set in the RRC message (if the frequency measurementinformation or frequency measurement list is set in the RRC message). Ifthe UE reselects a cell having the cell identifier contained in the areaconfiguration information and camps on again, the frequency measurementmay be restarted while the timer is running (if the timer has notexpired). Also, the frequency measurement configuration information maybe released or discarded when the timer indicating the frequencymeasurement duration expires.

-   -   1> When the UE receives the RRCRelease message (or when        receiving the RRCRelease message in response to the        RRCResumeRequest), and if the base station has not set the        frequency measurement configuration information in the        RRCRelease message or the UE has not received the frequency        measurement configuration information (or frequency measurement        list) through the RRCRelease message,    -   2> the UE receives or acquires frequency measurement        configuration information for the RRC idle mode or RRC inactive        mode frequency measurement from the system information (e.g.,        SIBS) of a camping cell and stores it. In addition, the UE may        perform or restart the RRC idle mode or RRC inactive mode        frequency measurement according to the frequency measurement        configuration information. In one alternative method, if there        is no frequency measurement configuration information in the        RRCRelease message, the UE may determine it as an instruction to        stop frequency measurement, stop the frequency measurement, stop        the timer, and discard the frequency measurement configuration        information or the frequency measurement result. In another        alternative method, the RRCRelease message may define an        indicator to discard or maintain the frequency measurement        configuration information or the frequency measurement result.    -   1> When the UE receives the RRCRelease message (or when        receiving the RRCRelease message in response to the        RRCResumeRequest), and if the base station has set the frequency        measurement configuration information in the RRCRelease message,        the UE has received the frequency measurement configuration        information (or frequency measurement list) through the        RRCRelease message, or a timer for frequency measurement is        running (if the timer has not expired),    -   2> the UE may discard the stored frequency measurement        configuration information or the frequency measurement result.        In one alternative method, the RRCRelease message may define an        indicator to discard or maintain the frequency measurement        configuration information or the frequency measurement result,        and may set to add, change, or delete only part of the stored        frequency measurement configuration information.    -   2> the UE stores or configures the frequency measurement        configuration information set in the RRCRelease message, and        performs or restarts the RRC idle mode or RRC inactive mode        frequency measurement according to the information.    -   1> If the system information of a cell on which the UE camps        indicates that the RRC idle mode or RRC inactive mode frequency        measurement is supported, or if the timer for frequency        measurement is running (if the timer has not expired),    -   1> Alternatively, if the UE camps or re-camps on a cell having a        frequency or cell identifier included in the area configuration        information (configuration information set in the RRC message        (e.g., RRCRelease)) for the RRC idle mode or RRC inactive mode        frequency measurement, or if the timer for frequency measurement        is running (if the timer has not expired),    -   2> if the base station does not set the frequency measurement        configuration information in the RRCRelease message, or if the        UE does not receive the frequency measurement configuration (or        frequency measurement list) in the RRCRelease message,    -   3> the UE receives or acquires the frequency measurement        configuration information for the RRC idle mode or RRC inactive        mode frequency measurement in the system information (e.g.,        SIBS) of a camping cell, and stores it.    -   3> the UE performs or restarts the RRC idle mode or RRC inactive        mode frequency measurement according to the frequency        measurement configuration information.    -   2> if the base station sets the frequency measurement        configuration information in the RRCRelease message, if the UE        receives the frequency measurement configuration (or frequency        measurement list) in the RRCRelease message, or if the timer for        frequency measurement is running (if the timer has not expired),    -   3> the UE performs or restarts the RRC idle mode or RRC inactive        mode frequency measurement according to the frequency        measurement configuration information set in the RRCRelease        message.    -   1> If the system information of a cell on which the UE camps        does not indicate that the RRC idle mode or RRC inactive mode        frequency measurement is supported, or if the timer for        frequency measurement is running (if the timer has not expired),    -   1> Alternatively, if the UE camps or re-camps on a cell having a        frequency or cell identifier not included in the area        configuration information (configuration information set in the        RRC message (e.g., RRCRelease)) for the RRC idle mode or RRC        inactive mode frequency measurement, or if the timer for        frequency measurement is running (if the timer has not expired),    -   2> the UE stops the RRC idle mode or RRC inactive mode frequency        measurement.    -   2> (The timer indicating the frequency measurement duration is        characterized by continuously running.)

FIG. 18 is a diagram illustrating operations of a terminal to perform afrequency measurement in an RRC idle mode or an RRC inactive mode andreport a measurement result according to an embodiment of thedisclosure.

In FIG. 18, upon receiving an RRC message, the UE drives a timer for RRCidle mode or RRC inactive mode frequency measurement, receives frequencymeasurement configuration information (if there is in the RRC message)for the RRC idle mode or RRC inactive mode frequency measurement (18-05)or receives the frequency measurement configuration information insystem information of a serving cell on which the UE camps through thecell selection or reselection procedure (18-05), and performs the RRCidle mode or RRC inactive mode frequency measurement (18-10). At thistime, the UE may perform the frequency measurement according to theabove-described first, second, third, or fourth embodiment. Then, the UEstores a frequency measurement result, stops the timer (18-05) uponreceiving message 4 when establishing a connection with a network ifthere is an indicator that the RRC idle mode or RRC inactive modefrequency measurement is supported in system information of the cell,and notify that there is a result of the RRC idle mode or RRC inactivemode frequency measurement through message 5. Then, when the basestation requests the result of the RRC idle mode or RRC inactive modefrequency measurement, the UE reports the measurement result (18-20),and may discard the measurement result when the measurement result issuccessfully delivered to the base station.

FIG. 19 is a signal diagram illustrating a structure of a terminalaccording to an embodiment of the disclosure.

Referring to FIG. 19, the terminal (i.e., UE) may include a radiofrequency (RF) processor 19-10, a baseband processor 19-20, a storage19-30, and a controller 19-40.

The RF processor 19-10 performs a function of transmitting and receivinga signal via a wireless channel, such as band conversion andamplification of a signal. That is, the RF processor 19-10 up-converts abaseband signal provided from the baseband processor 19-20 into an RFband signal, transmits the RF band signal via an antenna, anddown-converts an RF band signal received via the antenna into a basebandsignal. For example, the RF processor 19-10 may include a transmissionfilter, a reception filter, an amplifier, a mixer, an oscillator, adigital-to-analog convertor (DAC), an analog-to-digital convertor (ADC),and the like. Although only a single antenna is illustrated in thedrawing, the terminal may include a plurality of antennas. In addition,the RF processor 19-10 may include a plurality of RF chains. Moreover,the RF processor 19-10 may perform beamforming. For the beamforming, theRF processor 19-10 may control a phase and a size of each signaltransmitted or received via a plurality of antennas or antenna elements.In addition, the RF processor may perform MIMO, and may receive aplurality of layers while performing the MIMO operation. The RFprocessor 19-10 may appropriately configure a plurality of antennas orantenna elements according to the control of the controller, so as toperform reception beam sweeping, or may control the orientation of areception beam and a beam width so that a reception beam accords with atransmission beam.

The baseband processor 19-20 performs a function for a conversionbetween a baseband signal and a bit stream according to the physicallayer standard of a system. For example, in the case of datatransmission, the baseband processor 19-20 generates complex symbols byencoding and modulating a transmission bit stream. Further, in the caseof data reception, the baseband processor 19-20 reconstructs a receptionbit stream by demodulating and decoding a baseband signal provided fromthe RF processor 19-10. For example, in the case of data transmission,according to an OFDM (orthogonal frequency division multiplexing)scheme, the baseband processor 19-20 generates complex symbols byencoding and modulating a transmission bit stream, mapping the complexsymbols to subcarriers, and then configures OFDM symbols via an inversefast Fourier transform (IFFT) operation and cyclic prefix (CP)insertion. Further, in the case of data reception, the basebandprocessor 19-20 divides a baseband signal provided from the RF processor19-10 in the unit of OFDM symbols, reconstructs signals mapped to thesubcarriers via a fast Fourier transform (FFT) operation, and thenreconstructs a reception bit stream via demodulation and decoding.

The baseband processor 19-20 and the RF processor 19-10 transmit orreceive a signal, as described above. Accordingly, the basebandprocessor 19-20 and the RF processor 19-10 may be referred to as atransmitter, a receiver, a transceiver, or a communication unit. Inaddition, at least one of the baseband processor 19-20 and the RFprocessor 19-10 may include a plurality of communication modules so asto support many different radio access technologies. In addition, atleast one of the baseband processor 19-20 and the RF processor 19-10 mayinclude different communication modules to process signals of differentfrequency bands. For example, the different radio access technologiesmay include an LTE network, an NR network, and the like. Further, thedifferent frequency bands may include a super high frequency (SHF)(e.g., 2.5 GHz and 5 GHz) band and a millimeter (mm) wave (e.g., 60 GHz)band.

The storage 19-30 stores data, such as a basic program, an applicationprogram, and configuration information for the operation of theterminal. The storage 19-30 may provide stored data in response to arequest from the controller 19-40.

The controller 19-40 may include a multi-connection processor 19-42 andmay control the overall operation of the terminal. For example, thecontroller 19-40 transmits or receives a signal via the basebandprocessor 19-20 and the RF processor 19-10. In addition, the controller19-40 writes and reads data to/from the storage 19-40. To this end, thecontroller 19-40 may include at least one processor. For example, thecontroller 19-40 may include a communication processor (CP) thatperforms control for communication, and an application processor (AP)that controls a higher layer, such as an application program.

FIG. 20 is a block diagram illustrating a structure of a base station ina wireless communication system according to an embodiment of thedisclosure.

Referring to FIG. 20, the base station may include an RF processor20-10, a baseband processor 20-20, a backhaul communication unit 20-30,a storage 20-40, and a controller 20-50.

The RF processor 20-10 performs a function for transmitting or receivinga signal via a wireless channel, such as band conversion andamplification of a signal. For example, the RF processor 20-10up-converts a baseband signal provided from the baseband processor 20-20into an RF band signal and then transmits the converted signal via anantenna, and down-converts an RF band signal received via the antennainto a baseband signal. For example, the RF processor 20-10 may includea transmission filter, a reception filter, an amplifier, a mixer, anoscillator, a DAC, and an ADC. Although only a single antenna isillustrated in the drawing, a first access node may include a pluralityof antennas. In addition, the RF processor 20-10 may include a pluralityof RF chains. Moreover, the RF processor 20-10 may perform beamforming.For the beamforming, the RF processor 20-10 may control a phase and asize of each of the signals transmitted or received via a plurality ofantennas or antenna elements. The RF processor may perform a downlinkMIMO operation by transmitting one or more layers.

The baseband processor 20-20 performs a function of converting between abaseband signal and a bit stream according to the physical layerstandard of a first radio access technology. For example, in the case ofdata transmission, the baseband processor 20-20 generates complexsymbols by encoding and modulating a transmission bit stream. Further,in the case of data reception, the baseband processor 20-20 reconstructsa reception bit stream by demodulating and decoding a baseband signalprovided from the RF processor 20-10. For example, in the case of datatransmission, according to an OFDM scheme, the baseband processor 20-20may generate complex symbols by encoding and modulating a transmissionbit stream, map the complex symbols to subcarriers, and then configureOFDM symbols via an IFFT operation and CP insertion. In addition, in thecase of data reception, the baseband processor 20-20 divides a basebandsignal provided from the RF processor 20-10 in units of OFDM symbols,reconstructs signals mapped to sub-carriers via an FFT operation, andthen reconstructs a reception bit string via demodulation and decoding.The baseband processor 20-20 and the RF processor 20-10 transmit orreceive a signal, as described above. Accordingly, the basebandprocessor 20-20 and the RF processor 20-10 may be referred to as atransmitter, a receiver, a transceiver, a communication unit, or awireless communication unit.

The communication unit 20-30 provides an interface for performingcommunication with other nodes in a network.

The storage 20-40 may store data, such as, a basic program, anapplication program, configuration information, or the like, for theoperation of main base station. Particularly, the storage 20-40 maystore information associated with a bearer allocated to a connectedterminal, a measurement result reported from a connected terminal, andthe like. In addition, the storage 20-40 may store information which isa criterion to determine whether to provide or interrupt multiple-accessto a terminal. Also, the storage 20-40 may provide stored data inresponse to a request from the controller 20-50.

The controller 20-50 may include a multi-connection processor 20-52 andmay control the overall operation of the main base station. For example,the controller 20-50 transmits or receives a signal via the basebandprocessor 20-20 and the RF processor 20-10, or via the backhaulcommunication unit 20-30. In addition, the controller 20-50 writes andreads data to/from the storage 20-40. To this end, the controller 20-50may include at least one processor.

Although the present disclosure has been described with variousembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method performed by a terminal in acommunication system, the method comprising: receiving a radio resourcecontrol (RRC) release message including first information; performing,in case that the first information includes a first frequency of a firstfrequency list and a synchronization signal block (SSB) configurationfor the first frequency, a first measurement for the first frequencybased on the SSB configuration for the first frequency included in thefirst information, while the terminal is in an RRC idle mode or an RRCinactive mode; and performing, in case that the first informationincludes the first frequency of the first frequency list and does notinclude the SSB configuration for the first frequency, a secondmeasurement for the first frequency based on an SSB configuration forthe first frequency included in second information, while the terminalis in the RRC idle mode or the RRC inactive mode, wherein the secondinformation is received through a system information block (SIB).